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
fixed ADC initialization with skipped channels  - spotted by Lux.
Also increased ADC sample time to 239.5 cycles (~10uS at 24MHz ADC clock).
Merge branch 'master' of https://github.com/multiwii/baseflight
current sensor support added

also optimized the vbat code a bit