Replaced old mac os packaging script with instructions to build a clean keyhotee.dmg on mac os

The built .dmg is portable on all mac computers now given that keyhotee compiles cleanly with clang instead of gcc, and uses mac os’s native libc++ instead of gcc’s libstdc++ (which used to create conflicts before)
Merge pull request #258 from wackou/master

Replaced old mac os packaging script with instructions to build a clean ...