progress on drivers: px4fmu 1.7 I2C and SPI sensor drivers working

* MPU6000, MS5611, and HMC5883L drivers all work in test apps
* MS5611 driver hangs when you remove dead code uart driver, so there's
  some weird bug involving either drivers, freertos backend, or statemachine
  library - not sure what
px4 driver specific todo
freertos cm4 port: change vector table handler names to standard

- instead of xPortPendSVHandler, just PendSV_Handler, etc.
bump submodules
bump todo with build/os/platform specific issues
Merge branch 'px4-drivers' into development

Conflicts:
	smaccmpilot-stm32f4
bump todo