Insteon_Thermo: Add Derive_Link_State, Fix Typos, Check State Before Setting Cooling

Need custom derive_link_state to allow for custom link states.
Merge pull request #338 from krkeegan/Insteon_Thermo_Fix

Insteon_Thermo: Add Derive_Link_State, Fix Typos, Check State Before Setting Cooling
Merge branch 'master' of https://github.com/hollie/misterhouse