v0.19 firmware

Minla bootloader v0.02: minlaBootloader_v0.02.dfu
Minla firmware v0.19: minla_v0.19_firmware.bin
Minla GUI v0.01: minlaGUI_v0.01.jar

Notes:
v0.19 includes all features of v0.18-experimental plus:
- 4S lipo battery voltage sensing on pin 11
- various bug-fixes and minor improvements