V5.0.0.EU

• Fix issue where Start/Stop button will not work when charging timer is active OpenEVSE/ESP8266_WiFi_v2.x#184. Add new $F1 RAPI API to simulate a front button press. lincomatic#88
• Don't let $SC raise ampacity with V during over temperature event 2f84f96 17188f5
• Don't let $SC V increase ampacity above PP ampacity. Fixes lincomatic#90 with 739ac3f
• Overcurrent cutout implemented. If EV draws more current than the pilot setting charging will hard stop. Fixes lincomatic#87 with lincomatic@60b5083
• Don't allow volatile current capacity > EEPROM value lincomatic@ac5dbb0
• don't allow SetCurrentCapacity() above PP max lincomatic@1c51eea

Full change log:

20180523 SCL
- when RTC not defined, g++ bug pops out:
	open_evse:2384: error: unable to find a register to spill in class 'NO_REGS'
  -> add GPPBUGKLUDGE
	
D5.0.0 20180518 SCL
- implement $F1 RAPI command to simulate front panel short press
- SAFETY: don't allow $SC to raise current capacity during over temperature event
- SAFETY: SetCurrentCapacity() -> when nosave set, don't allow current capacity to be
	raised above EEPROM value
	-> don't allow $SC with V to raise current capacity above value in EEPROM
	-> don't allow PP to set current capacity higher than EEPROM
- PP code cleanup
- don't allow SetCurrentCapacity() to go above PP value
- implement over current protection. if OVERCURRENT_THRESHOLD is set,
	then if EV draws >= OVERCURRENT_THRESHOLD amps for >=
	OVERCURRENT_TIMEOUT ms -> hard fault