This commit makes the code (mostly) C99-compatible, enabling to compile it without the -Wno-error=implicit-function-declaration flag. This way, Magic becomes usable on arm64 architectures, specifically on Apple computers with M1/M2 SoC.
Specifically, fixed the initial background, display of text, reinstated supercolor values, and fixed the backing store coordinates.
Alessandro De Laurenzis
Tim 'mithro' Ansell
Tim Edwards