Umoria 5.7.0 Restoration Release

Notable changes

• Windows, macOS and Linux support.
• Renaming binary from moria to umoria, save file to game.sav,
  and scores to scores.dat.
• Use clang-format/-tidy to clean up the code formatting.
• Moves all standard library header includes into one file.
• Replaces custom types (e.g. int8u, int16u, etc.) with their equivalent
  C standard types.
• Introduce the _Bool type.
• Converts deprecated K&R style function declarations.
• Refactor all comments.
• Reorganise all old document files, create a historical directory.

Deprecated

• Remove support for discontinued computers and OS: Atari ST, Amiga, MS DOS,
  "Classic" Mac OS (pre OS X), VMS, System III, etc., etc.