Make it build
Merge pull request #154 from davibe/master

Make it build
Revert last makefile change - wasn't needed, user error.
building hex with latest changes - improved althold; improved NMEA parser; other misc fixes
building hex with latest changes - improved althold; improved NMEA parser; other misc fixes
Adding remainder of CJMCU support
revert makefile change, that was mistake
cleanup hardware revision detection and get rid of checks for hse_value
add spi autodetect functionality, actually check for currently used M25P16 flash chip
Get rid of rev4 PB13 usage
FrSky telemtry: Put Vfas battery voltage in again
Merge pull request #157 from cody82/master

FrSky telemetry: Put Vfas battery voltage in again
Initial stab at supporting MPU6500.
Make I2C driver fail gracefully when I2C hardware hasn't been initialized (on boards w/o I2C sensors)
Also fixes CJMCU build target to include SERIAL_RX features.
Add support (untested) for remapped USART3 w/DMA transfer
Update README.md
Slight cleanup of MPU6050 driver to use same constants as MPU6500. Both drivers should probably get merged, the operation is nearly identical with only bus access being different.
It helps to enable clock to correct peripheral (Fixing USART3 APB1)
Add conditionals to GPS code in CLI - don't compile them in without #define GPS
Add support for MSP FlexPort on USART3. Make MSP transmission listen and respond on several ports. (CLI still only works on MainPort).
Cleanup serdes code so it doesn't look as ugly.
Add conditionals for GPS MSP to allow compiling them out.
USART3 didn't actually need remapping, duh!
Fix initialization period for MPU6500, would cause strange effects if not followed.