[bugfix-2.0.x] Fix compiler error (issue #7730)

[2.0.x] HAL for STM32F1

[2.0.x] User menu return-to-status option

Adding files for STM32F1 HAL based on libmaple/stm32duino core.
Current persistent_store uses cardreader changes to be sent in separate
commit, but could be changed to use i2c eeprom.

Some HAL formatting cleanup

Fixes for GT2560, ANET A8

Fixes for 2 "... not declared in this scope" compiler errors.

For PR #7738

[2.0.x] Fix G3D_PANEL encoder steps, babystep label #7762

Comes from #7760

Comes from #7760

See PR #7593

See #7725

Added missing include file,
called 'leveling_is_active()' with no prototipe defined.

As pointed out by @marcio-ao in #7638

G33 changes from 1.1.x

[bf20ng] Improve AVR arch detection

Replace ARDUINO_ARCH_AVR with __AVR__ to better detect architecture for non-Arduino dev environments.  Resolves compile failure in PIO for 8-bit Teensduino targets

More info:
https://forum.pjrc.com/threads/33234-Using-Teensyduino-Selecting-Teensy-3-2-3-1-board-has-incorrect-platform-define
http://www.atmel.com/webdoc/avrlibcreferencemanual/using_tools_1using_avr_gcc_mach_opt.html

Apply LCD changes from 1.1.x

Changes from #7720

[2.0.x] Group G-codes to fix command-line overflow

Addressing #7707

Move LPC1768 framework out of Marlin source folder

[PR] [Marlin 2.0] Fix compiler warning message