DSC PC3000 Support + Unlocker

[sfossen]

TLDR:

• fix multi-char writer
• refactor to reduce repeated code
• refactor print functions
• refactor interrupt handlers
  • reversed the bit order in interrupt to make data compatible with powerseries
  • reversed byte order to stablize indexes and simplify loops
  • switch to ring buffer to stabilze reading
• added state machine to track keys/lights/states
• fixed unlocker to work with classic series