Tic-80: Special functions should have common formatting

[ambyra]

TIC and OVR are 3 characters, all caps. scanline() should be SCN or something to match. Also, all tic80 special functions should match this format or be otherwise standardized.

[nesbox]

they could be, but what about backward compatibility?
users created a lot of games with lowercase scanline()

[ambyra]

Have both, mark scanline deprecated. It would be good to have official looking functions that are consistent.

[nesbox]

ok, I added SCN callback and now all the callbacks have 3 chars names: TIC SCN OVR e0cc606

old scanline also works, but not highlighted in the Code Editor