Re-factoring logic into roast_state and advance_state()

- Updated roast_state with new states
- Added advance_state function
- Removed switch
- Converting all comments to ANSI C /* type */
- Replaced ELEMENT_STATE with HEAT_STATE
- Moved heat_state and fan_state logic into roast_state
- Added SERIAL define for enabling serial output
- Removed AUTOSTART functionality
- Re-organized pin, constants
- Switching from functional to C style casting
- Added missing ms_to_min prototype
- Renamed minutes to min
- Moved elapsed time to global
- Added unsigned long roast_start
- Added target set helper functions
- Re-factored state switching functions
- Moved all debug output to end of functions
Adding roast_idle() function