RFControl::phase() allows you to add either a HIGH or LOW entry (i.e. a single phase of a pulse. RFControl::add() continues to add a full HIGH/LOW pulse so these changes are fully backwards compatible.
Instead of pre-defining RF433 and RF315, the user should define their own RFControl{pin} as a variable in their device-specific DEV_*.h file. Makes RFControl more generic and not specific to any transmitter name (such as 433 or 315). Also means that the pin can be set by the user instead of having to modify RFControl.h deep in the library.
Gregg