Addressing #7264

As proposed in #7429

* Fix compilation of ADVANCED_PAUSE_FEATURE without SDSUPPORT

* Fix Identation

* Make use of IS_SD_PRINTING macro

as per @MagoKimbra

Add a parameter to enable/disable audible user script feedback

Add
MSG_BLTOUCH                    
MSG_DELTA_SETTINGS            
MSG_UBL_MESH_EDIT                
MSG_UBL_OUTPUT_MAP_BACKUP        
MSG_UBL_STEP_BY_STEP_MENU       
MSG_Z_FADE_HEIGHT

Fix regression in #7428

LCD_BED_LEVELING requires PROBE_MANUALLY with auto bed leveling enabled.  See #7396

Filament change causes freeze during paused print. This PR disables Filament change in the prepare menu when a print from SD Card is paused. See #7395

Axis would only move when homing.
Bug introduced in 91841d75c9.
Fixes #6956, fixes #7050 and fixes #7291

USBCON is definied by serial.h pullikng in MarlinConfig.h which in turn pulls in Arduino.h.  Defining in later includes has shown to cause compile issues so removing all extraneous calls for and potentially easier future linker troubleshooting.
more USBCON unification

Connected as described at http://printrbot.com/shop/led-strip/

Based on patch by Kelly Anderson <kelly@xilka.com> at
http://www.xilka.com/printrbot/marlin/1.1.4/20170707/

Signed-off-by: Alexey Shvetsov <alexxy@gentoo.org>

This allows the use of D4 as PS_ON since MKS Gen doesn't have a PS_ON pin. However this effectively allows only 3 servos (instead of 4).

Signed-off-by: Alexey Shvetsov <alexxy@gentoo.org>

Add more details as requested in #7198

Without this...  The LSF won't work because none of the sampled points
in this code block get added.

This was broken by 9af67e2446.

We can save more and a pile of RAM by eleminating the eqnBVector and
EqnAMatrix arrays next.