Add custom wiring.c for FX support

[ace-dent]

With new developers discovery the platform via the Arduboy FX, it may not be clear how to add @MrBlinky's 'up+down' reset function. Should this custom wiring.c be added to the library?

Ref. https://community.arduboy.com/t/solved-how-to-add-the-up-down-reset-function-to-my-game/9931/2

[MLXXXp]

wiring.c is one of the base low level files of the Arduino system. I don't feel the Arduboy2 library is the appropriate place to provide a customised replacement for it.

I think it would be best if this were done by the Arduboy board package. Also, it should be considered whether the entire core directory be forked instead of just the wiring.c file. Once forked, the file(s) would have to be regularly maintained to include any changes, enhancements or bug fixes made to the originals, as deemed desirable or necessary.