Update after discussions on IRC:
* operating system specific path retrieval is moved back to GHOST, nothing blender specific here though
* cleaned up path functions a bit to remove #ifdefs
* removed Cocoa from blenlib again
TODO:
* Matt, Damien, please check and correct the functions for Cocoa and Carbon, could only put back existing code but needs adjustment
* finish GHOST_getBinaryDir - this should replace the BLI_where_am_i eventually as well as BLI_getInstallationPath on Windows and get_install_dir for the blenderplayer runtime
* It would probably be nice to define GHOST_getTempDir as well and move those out
* more cleanups...
NOTE:
Things are likely broken for macs
