v1.5.0 - Add external script controlled zones

New Feature: Zones controlled by external script
If you set your output type to "None" in settings and a script with execute permissions exists at /usr/local/bin/sprinklers_pi_zones (changeable in config.h) it will be called with the arguments [zone number] and 0/1 for off/on respectively. eg. /usr/local/bin/sprinklers_pi_zones 1 1 would turn on zone 1.
Due to the way we manage I/O pins whenever state changes we will call it for every zone with its current state, even if it hasn't changed.
You can do whatever you want with this information, if you want to have some locally controlled pins and some external pins you can manually pass through to the command line version of wiring pi for the local pins.