[MacOSX] push the MacOS dir into the PATH, not the Resources dir.
[MacOSX] Use the Contents dir instead of the Contents/Resources dir as our base
[MacOSX] Check env variables to see if we already have the values instead of using LAUNCHER env hacks

Attempted fix for bug #24011
[MacOSX] Maintain backward compatibility with older XS/mtouch
[MacOSX] code cleanup
[MacOSX] Added debugging
[MacOSX] Fixed recursion and removed debug printf's
Merge pull request #666 from mono/bug24011

Fixed PATH env when re-launching from the updater