Updated imgui, utils/time using more C++11 features

include/utils/time.h

 #ifndef _UTILS_TIME_H_
 #define _UTILS_TIME_H_
 
+using or_time_t = unsigned long;
+
 /*!
  * \brief Read the system timer
  * \returns number of ticks
  */
-unsigned long systemTimerGet();
+or_time_t systemTimerGet();
 
 /*!
  * \brief Reset the system timer

src/deps/imgui/imconfig.h

 //---- Don't implement default clipboard handlers for Windows (so as not to link with OpenClipboard() and others Win32 functions)
 //#define IMGUI_DISABLE_WIN32_DEFAULT_CLIPBOARD_FUNCS
 
-//---- Include imgui_user.cpp at the end of imgui.cpp so you can include code that extends ImGui using its private data/functions.
-//#define IMGUI_INCLUDE_IMGUI_USER_CPP
+//---- Include imgui_user.inl at the end of imgui.cpp so you can include code that extends ImGui using its private data/functions.
+//#define IMGUI_INCLUDE_IMGUI_USER_INL
 
 //---- Define implicit cast operators to convert back<>forth from your math types and ImVec2/ImVec4.
 /*
 */
 
 //---- Freely implement extra functions within the ImGui:: namespace.
-//---- Declare helpers or widgets implemented in imgui_user.cpp or elsewhere, so end-user doesn't need to include multiple files.
+//---- Declare helpers or widgets implemented in imgui_user.inl or elsewhere, so end-user doesn't need to include multiple files.
 //---- e.g. you can create variants of the ImGui::Value() helper for your low-level math types.
 /*
 namespace ImGui

src/deps/imgui/imgui.cpp

  API BREAKING CHANGES
  ====================
 
+  - 2014/10/02 (1.14) renamed IMGUI_INCLUDE_IMGUI_USER_CPP to IMGUI_INCLUDE_IMGUI_USER_INL and imgui_user.cpp to imgui_user.inl (more IDE friendly)
   - 2014/09/25 (1.13) removed 'text_end' parameter from IO.SetClipboardTextFn (the string is now always zero-terminated for simplicity)
   - 2014/09/24 (1.12) renamed SetFontScale() to SetWindowFontScale()
   - 2014/09/24 (1.12) moved IM_MALLOC/IM_REALLOC/IM_FREE preprocessor defines to IO.MemAllocFn/IO.MemReallocFn/IO.MemFreeFn
  ISSUES & TODO-LIST
  ==================
 
- - misc: merge ImVec4 / ImGuiAabb, they are essentially duplicate containers
+ - misc: merge or clarify ImVec4 / ImGuiAabb, they are essentially duplicate containers
  - window: autofit is losing its purpose when user relies on any dynamic layout (window width multiplier, column). maybe just discard autofit?
- - window: support horizontal scroll
- - window: fix resize grip scaling along with Rounding style setting
+ - window: add horizontal scroll
+ - window: fix resize grip rendering scaling along with Rounding style setting
  - widgets: switching from "widget-label" to "label-widget" would make it more convenient to integrate widgets in trees
  - widgets: clip text? hover clipped text shows it in a tooltip or in-place overlay
  - main: make IsHovered() more consistent for various type of widgets, widgets with multiple components, etc. also effectively IsHovered() region sometimes differs from hot region, e.g tree nodes
  - shortcuts: add a shortcut api, e.g. parse "&Save" and/or "Save (CTRL+S)", pass in to widgets or provide simple ways to use (button=activate, input=focus)
  ! keyboard: tooltip & combo boxes are messing up / not honoring keyboard tabbing
  - keyboard: full keyboard navigation and focus.
+ - input: reowrk IO to be able to pass actual events to fix temporal aliasing issues.
  - input: support trackpad style scrolling & slider edit.
  - tooltip: move to fit within screen (e.g. when mouse cursor is right of the screen).
  - misc: not thread-safe
     MousePosPrev = ImVec2(-1,-1);
     MouseDoubleClickTime = 0.30f;
     MouseDoubleClickMaxDist = 6.0f;
+    UserData = NULL;
 
     // User functions
     RenderDrawListsFn = NULL;
 void ImGuiIO::AddInputCharacter(ImWchar c)
 {
     const size_t n = ImStrlenW(InputCharacters);
-    if (n < sizeof(InputCharacters) / sizeof(InputCharacters[0]))
+    if (n + 1 < sizeof(InputCharacters) / sizeof(InputCharacters[0]))
     {
         InputCharacters[n] = c;
         InputCharacters[n+1] = 0;
 static inline float  ImLength(const ImVec2& lhs)                                { return sqrt(lhs.x*lhs.x + lhs.y*lhs.y); }
 
 static int ImTextCharToUtf8(char* buf, size_t buf_size, unsigned int in_char);                                // return output UTF-8 bytes count
-static int ImTextStrToUtf8(char* buf, size_t buf_size, const ImWchar* in_text, const ImWchar* in_text_end);   // return output UTF-8 bytes count
+static ptrdiff_t ImTextStrToUtf8(char* buf, size_t buf_size, const ImWchar* in_text, const ImWchar* in_text_end);   // return output UTF-8 bytes count
 static int ImTextCharFromUtf8(unsigned int* out_char, const char* in_text, const char* in_text_end);          // return input UTF-8 bytes count
-static int ImTextStrFromUtf8(ImWchar* buf, size_t buf_size, const char* in_text, const char* in_text_end);    // return input UTF-8 bytes count
+static ptrdiff_t ImTextStrFromUtf8(ImWchar* buf, size_t buf_size, const char* in_text, const char* in_text_end);    // return input UTF-8 bytes count
 
 static int ImStricmp(const char* str1, const char* str2)
 {
     return 0;
 }
 
-static int ImTextStrFromUtf8(ImWchar* buf, size_t buf_size, const char* in_text, const char* in_text_end)
+static ptrdiff_t ImTextStrFromUtf8(ImWchar* buf, size_t buf_size, const char* in_text, const char* in_text_end)
 {
     ImWchar* buf_out = buf;
     ImWchar* buf_end = buf + buf_size;
 {
     if (c)
     {
-        int i = 0;
-        int n = (size_t)buf_size;
+        size_t i = 0;
+        size_t n = buf_size;
         if (c < 0x80) 
         {
             if (i+1 > n) return 0;
     return 0;
 }
 
-static int ImTextStrToUtf8(char* buf, size_t buf_size, const ImWchar* in_text, const ImWchar* in_text_end)
+static ptrdiff_t ImTextStrToUtf8(char* buf, size_t buf_size, const ImWchar* in_text, const ImWchar* in_text_end)
 {
     char* buf_out = buf;
     const char* buf_end = buf + buf_size;
 
 //-----------------------------------------------------------------------------
 
-//---- Include imgui_user.cpp at the end of imgui.cpp so you can include code that extends ImGui using its private data/functions.
-#ifdef IMGUI_INCLUDE_IMGUI_USER_CPP
-#include "imgui_user.cpp"
+//---- Include imgui_user.inl at the end of imgui.cpp so you can include code that extends ImGui using its private data/functions.
+#ifdef IMGUI_INCLUDE_IMGUI_USER_INL
+#include "imgui_user.inl"
 #endif
 
 //-----------------------------------------------------------------------------

src/deps/imgui/imgui.h

     ImWchar     FontFallbackGlyph;          // = '?'                    // Replacement glyph is one isn't found.
     float       PixelCenterOffset;          // = 0.0f                   // Try to set to 0.5f or 0.375f if rendering is blurry
 
+    void*       UserData;                   // = NULL                   // Store your own data for retrieval by callbacks.
+
     //------------------------------------------------------------------
     // User Functions
     //------------------------------------------------------------------
     bool        KeyCtrl;                    // Keyboard modifier pressed: Control
     bool        KeyShift;                   // Keyboard modifier pressed: Shift
     bool        KeysDown[512];              // Keyboard keys that are pressed (in whatever order user naturally has access to keyboard data)
-    ImWchar     InputCharacters[16];        // List of characters input (translated by user from keypress+keyboard state). Fill using AddInputCharacter() helper.
+    ImWchar     InputCharacters[16+1];      // List of characters input (translated by user from keypress+keyboard state). Fill using AddInputCharacter() helper.
 
     // Function
     void        AddInputCharacter(ImWchar); // Helper to add a new character into InputCharacters[]

src/utils/time.cpp

 #include "global.h"
 #include "utils/time.h"
 
-static unsigned long systemTimerStart = 0;
+static auto systemTimerStart = std::chrono::steady_clock::now();
 
-unsigned long systemTimerGet() {
+or_time_t systemTimerGet() {
     auto tp = std::chrono::steady_clock::now();
-    auto dtn = tp.time_since_epoch();
-    return (dtn.count() * 1000 * std::chrono::steady_clock::period::num
-            / std::chrono::steady_clock::period::den) - systemTimerStart;
+
+    return static_cast<or_time_t>(
+            std::chrono::duration_cast<std::chrono::milliseconds>
+            (tp - systemTimerStart).count());
 }
 
 void systemTimerReset() {
-    auto tp = std::chrono::steady_clock::now();
-    auto dtn = tp.time_since_epoch();
-    systemTimerStart = dtn.count() * 1000 * std::chrono::steady_clock::period::num
-            / std::chrono::steady_clock::period::den;
+    systemTimerStart = std::chrono::steady_clock::now();
 }