Also removed explicit platform HAL directory inclusion from platformio.ini to make sure these errors are caught by Travis in the future

HardwareSerial has been tested on Uart0 (debug header) and Uart3 (i2c connector)
Software Serial has been tested to work bi-directionally at 9600 and 115200
using pins 6 and 63 on J5, and unidirectionally (write only) at 250000.
The code used to test was Teemuatlut's tmc2208 patch, and a few small changes to main used to echo recieved chars back to a host pc.

Uses PWM1 to directly control pins 4, 6 & 11 (servo 0, 1 & 3) and PWM1
generated interrupts to control other pins.

Interupt control of the servo pins had too much jitter so switched all
that we could to PWM1 direct control.  The PWM1 direct control pins have
less than 1 microsecond pulse width jitter while the interrupt
controlled ones can have 20+ microseconds of jitter.

Also added insurance to the servo code in the "disable servo after move"
section.

* LCD_UBL_memory_slot_corrections

Changed the memory slot edit function to work with the
`settings.calc_num_meshes()`

* Add a little more safety margin...

* More corrections

Error handling when the EEPROM is not available.

Mostly...  clean up some compile time warnings for the 20x4 LCD Display.

* UBL_correction

* RGB Map function

move from legacy precise to trusty build image
fix PATH not including buildroot/bin
remove symolic link to ~/bin as trusty travis image doesn't include it in PATH anyway