[2.0] Add platformio support for stm32

* 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

fix Travis error

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.

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

Implement AVR Platform