P-ROC: use helper functions to read PRPinmame section of YAML
P-ROC: generalize ConfigureWPCFlipperSwitchRule()
Allow for more complicated flipper switch rules, plus disabling of rules (by setting a zero coil count).  Required by a later commit to disable flippers when the ball trough is full.
P-ROC: add optional feature to disable flippers on full ball trough
If fullTroughDisablesFlippers is set to 1 in the PRPinmame section of the machine's YAML, PinMAME will disable the flipper coil rules (created by the PRFlippers section of the YAML) whenever all trough switches (trough1 through troughX) are active.