Added o, u, NO REFUND

Changed O to o, to easier distinguish between zero and o.
Added NO REFUND, to display when the machine is out of return coins.
Added big O again

The big o can be used in the context of displaying text strings.
An example is COLA, which looks better than CoLA.
Syntax error
Merge branch 'master' of https://github.com/Lauszus/ArduinoVendingMachine

Conflicts:
	ArduinoVendingMachine.h
Merge branch 'master' of https://github.com/Lauszus/ArduinoVendingMachine
Enable pullup resistor to make sure we don't check coins by mistake
Specify error messages, to make it easier to figure out if a slot is is empty or the motors are stuck
Fixed stability issue with Return button + changes to scrolling text (dry when slot is empty, jam when motor is stuck) + improved when NO REFUND is shown
Fixed header
Updated comments
Made scrolling text non-blocking for other text
Store total coins in EEPROM

Used for debugging