Fix _tx_active handling for Wire Slave

Correct SPI state machine for disable()

Update dfu-utils for macosx

Rework stm32l4_servo.c to use the EVENT_PERIOD to sequence throu the …

…timeout

Fix various typos in boards.txt and variants.h for Ladybug; remove de…

…ad code in hooks.c

Update README.md to have meaningful install instructions

Update variants and compile flags for consistency

Add ST-Link/OpenOCD support as a programmer

Add ST-Link/OpenOCD support as a programmer

Add RTC support