(bionic doesn't include g++7 ppa)

Also fix use_example_configs

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

Support env MARLIN_LANGS for user select generated language, and update doc; update script to generate dogm_font_data_ISO10646_1.h automatically.

Enable 6th-order jerk-controlled motion planning in real-time.
Only for 32bit MCUs. (AVR simply does not have enough processing power for this!)

- `M666` is static, not inline
- Disambiguate some stepper macros

- This status screen uses the ST7920 character generator to greatly
  reduce SPI traffic and MCU load when updating the status screen.

- Has been tested with the RepRapDiscount Full Graphics Smart Controller
  but should work with any LCD that uses an ST7920 or fully compatible
  controller.

Updating I2C position encoders to enable babystepping and Babystep XY when using the ecm microstep correction method. Also changed default method to ECM microstep.

* Add option to use Neopixel as case light

* Apply CASE_LIGHT_USE_NEOPIXEL to example configs

WORKS!

11 line caches PIO packages (toolchains, libs) which is very good! This PR will force PIO to find updates for installed libs and packages.