teensy/controller*: moved to cpp
teensy/Loop: add initial impl of the main loop
teensy/controller.c: remove old c version of the controller
teensy/config.h: move configuration to separate .h file
teensy/main.cpp: update to use new main loop
teensy/src/version.h: bump version 3 -> 4
coffee: add utility for controlling silvia
coffee/.gitignore: initial import