IMU Updates

[guyfleeman]

The IMU code is pretty bare bones. This should address the motion improvement requirements set by @joe-spall. I suggest:

• Move the IMU reads into their own task
• Have the task block on device interrupts
• Enable interrupts on the BMI085 after gyro conversion, fire SPI DMA transfer
• Double check the BMI085 settings for data rate vs noise. It may be updating much faster than we need and would have noise
• Add an optional filter
• Add accelerometer data fetching at the same time we use DMA to get the gyro data (these may have different acq rate, prioritize gyro)

There's already a pubsub channel setup for IMU data that collin used for the o.g. prototype. This should be task/thread safe.