-Enable boards_dir option in PIO INI
-Remove defunct custom board file operations for PIO auto-build environment
-Remove now-defunct Teensy++ 2.0 PIO entry, replaced by `at90USB1286_DFU` and `at90USB1286_DFU` (using this entry always put AT90USB board boot loaders in jeopardy of being overwritten due to the very small size of the official Teensy++ 2.0 bootloader)
-whitespace

According to https://github.com/MarlinFirmware/Marlin/issues/9917#issuecomment-399204568

[2.0.x] Fix value editing (with callback)

See https://github.com/MarlinFirmware/Marlin/issues/5597#issuecomment-397683325

The registers within the Max7219 can get corrupted a number of ways.  This allows the Max7219 to be reset and fully initialized.
And...  it also allows the user to see the initialization pattern.

Fix message to long for 12864 display

HAL for Espressif ESP32 WiFi

Added reset bltouch instead. This ensure properly stow even when in error.

[2.0.x] Fix stepper pulse minimum period and timing calculations

Fix #8890

Always honor minimum period on stepper pulse generation, and fix timing calculations

Signed-off-by: etagle <ejtagle@hotmail.com>

[2.0.x] Updates for junction_deviation_mm

- Drop `max_jerk` with `JUNCTION_DEVIATION`
- Add `max_e_jerk_factor` for use by `LIN_ADVANCE`
- Recalculate `max_e_jerk_factor` when `junction_deviation_mm` changes
- Fix LCD editing of `junction_deviation_mm`

- Enable / disable interrupts with `__iSeiRetVal` / `__iCliRetVal`
- Add STM32F1 to Travis CI tests

An undocumented hw bug makes the UART lose chars when RX ISR is disabled, even for a very small amount of time. This happens when RX_BUFFER > 256, and the result is corrupted received commands. Solved by implementing pseudo-atomic operations on 16bit indices.