Fix/improve ros integration

Changes:
- Units of acceleration are now m/s^2, in agreement with ROS convention.
- Cleaned up code base, replaced error codes with exceptions.
- Status can now be viewed from `rqt_runtime_monitor`.
- Filter output is now in a single, custom message with covariances and important status flags.
- Added option to enable/disable accelerometer update in the estimator.
- Removed TF broadcast option.
- Reformatted code base to clang-llvm convention.