minor frontend adjustements
refactor build
migrate to using mavlink
cleanup
add dummy components to frontend
implement serial backend functionality
hand-implement some messages
add further support for mavlink
notes:
* the protocol seems bloated for our needs
* I'm not sure about the handling of primitive types in the protocol, especially the scalajs handling of numeric types of different widths seems cumbersome
propagate mavlink messages to ui
add battery status message