v4.0.7

v4.0.7

• Added unit testing in tests/ directory
• Added zig build option
• extras/menu.h - New widget added for adding a vertical scrolling menu
• extras/border.h - New widget added for drawing borders around a given
  vector of strings
• screen.h - Added hashing for Pos object to use as a key in
  std::unordered_map and other hashed objects
• text.h - Add raw_str function to strip a string of any added ansi escape
  codes
• Added new examples:
  • examples/vertical_menu.cpp for trialing menu.h
  • examples/game.cpp porting a simple "collect the coin" game to Rawterm
  • examples/borders.cpp for a simple display of how to use border.h