automatically split C into separate functions

[zliu41]

This does not include splitting C into separate files

We should basically be able to kFunctionCall without kFunctionCall, making C functions correspond to Haskell functions, and tuning it to a level that minimizes build time and/or minimizes run time (although I don't expect it would have a lot of effect on the latter, as the C compiler should be able to handle that well enough)

This reduces control law maintenance while getting us another step toward readable C and improving performance.

(Extricated from https://kitty-hawk.atlassian.net/browse/SW-3980)