Central heating control on an Arduino

V0.4 Change so that 1 minute in 10 cycling uses residual heat from the boiler for the 1st minute (or stays in overrun) and doesn't call for heat until into the second minute. Most timing values moved to #define constants at the start of the project file.

V0.3 Mainly added a delay to the stat class to be able to wait for DEMAND to be longer than a minute before responding. This is to circumvent short boiler firing when the RoomStat is cycling heat for 1 minute in 10. (The problem was actually with the honeywell system cos a HR80 had become detached from its base.)

V0.2 Refactored code. (Tidy up). Made the loop a bit prettier - added debug comments. This is the 1st main working version

V0.1 Base build. Kinda worked.