* Update light state when transformer has finished
* Revert writing direct to output
* Correct handling of zero-length light transformers
* Allow transformers to handle zero-length transitions, and check more boundary conditions when transitioning back to start state
* Removed log.h
* Fixed race condition between LightFlashTransformer.apply() and is_finished()
* clang-format
* Step progress from 0.0f to 1.0f at t=start_time for zero-length transforms to avoid divide-by-zero
