Semaphore Controller
-- WIP --
ATTiny 85 controller for a simple 4 state semaphore.
Controller is waiting for interruptions (ex: pulse switch) on a specific pin (PB1) to alternate between states:
off -> red -> yellow -> green
Each state (except off) corresponds to a specific output pin with an attached led: PB4 (red), PB3 (yellow), PB0 (green)