* Move units into API docs instead because suffixes make user code verbose and hard to read
* Rename trackWidth to trackwidth
* Make ultrasonic classes use meters instead of a mix of m, cm, mm, ft,
and inches
This required changing the constant values (e.g. kSize) into functions
(e.g. GetSize()).
Fixed implementations of ForEachNested to be inline (as these are actually
templates).
Also added a ntcore Struct test.
This implements de/serialization for the types that aren't templated (SwerveDriveKinematics) in C++ or where there is no trivial way to go round-trip (Splines) for the messages.
