added new checker that runs through unity, not mdtool

seems a bit slower but we can use it for unit tests.
half-finished comment is COMPLETED
refactor the unity checkers a little to make creating varients easier
flychecker for running tests

although it fails if tests are outside current buffer??
new function compile-unity-tests that runs unity test output through compile buffer

with regexp to parse output
mdtool is default unity flychecker, and bound test compiler to C-c t