Add platform independent reversible code

[tolauwae]

WARDuino/src/Primitives/arduino.cpp

Lines 511 to 522 in 296fffd

	def_prim_reverse(chip_digital_write) {
	for (IOStateElement state : external_state) {
	if (!state.output) {
	continue;
	}
	if (state.key[0] == 'p') {
	invoke_primitive(m, "chip_digital_write", stoi(state.key.substr(1)),
	(uint32_t)state.value);
	}
	}
	}

This code will likely be the same for all chip_digital_write primitives, regardless of platform. Since you are just invoking the primitive.

(in fact this will the strategy for most primitives)

I think we can generalize this and move to a reversibility file to avoid code duplication. In will make implementing the reversibility for other primitives easier as well.

Originally posted by @tolauwae in #250 (comment)