When the buffer is empty index_write == index_read, but they needed constrained by buffer_mask

* fixed some include paths

* LPC1768: Fix Serial API

Add missing serial methods used if TX_BUFFER_SIZE is set
Change return value of HalSerial:read to match Arduino API

* LPC1768: add filters to ADC

This is to try and compensate for hardware issue and oversensitivity to noise

* LPC1768: remove the polling section of delayMicroseconds

* LPC1768: lock usb mass storage device while device accesses it.

Currently only applicable to persistent store,
The device always has priority and will unmount the sd card from the host, Windows then tries to automount again so it can look like the explorer window freezes. Linux Mint, by default, just closes the Nemo window.

* Add timeout to make sure if Serial never connects that Marlin still boots

* Remove unneeded ifdef CPU_32_BIT

In general the need for ifdef CPU_32_BIT blocks means that something is missing from the HAL API or a Platform, in this case HAL_TICKS_PER_US was missing from the AVR Platform

* LPC1768: relocate RE-ARM debug_extra_script.py

[2.0.x] Add XON/XOFF serial handshaking

[2.0.x] Fix DUAL_X_CARRIAGE manual move

Followup to #7750, #7826

Also reformat and document

From @ejtagle, originally #7459

[2.0.x] Fix broken M600 resume_print

[2.0.x] Option to disallow motion before homing

Derived from #7811 and #7779

Cleanup 2.0.x compiler warnings

gitignorefix

Fix G10/G11 with synchronize

Marlin 2.0.x - fix LPC1768 stepper hang and limit maximum stepper ISR spacing

[2.0.x] Fix Servo class compile errors

[2.0.x] Fix LPC1768 USB interrupt priority

2.0.x Re-ARM compile issues - work around

Marlin 2.0.x - M355 fixes & LCD improvements

fix Travis error

[2.0.x] Show leveling status on character LCD

[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