remove i2c driver function calls and directly read/write I2C->DR
reformat I2C driver and align comments. add timeout checking and move hardware reinit common code into separate function.
moved nvic priority group init into drv_system, where it belongs
Remove FY90Q support. Dead hardware, not even available anymore, and doesn't offer anything over already cheap acroafro.
fixed ADC initialization with skipped channels  - spotted by Lux.
Also increased ADC sample time to 239.5 cycles (~10uS at 24MHz ADC clock).
current sensor support added

also optimized the vbat code a bit
Merge pull request #113 from luggi/Powermeter

Current sensor support added, with defaults for Allegro ACS758 current sensor.
formatting fixes and rename one of ADC channels.
fixed frsky temeletry gps output to match with what is actually expected. props to KC_703 for spotting this stuff.
new Baseflight PID

full gyro scale is used now
and a new pid with float calculations and proper units is added based on PIDrewrite
eeprom size is also increased from 1kB to 2kB

Conflicts:
	src/config.c
	src/imu.c