Implement turfs_init() and turfs_quit() on OS X

Signed-off-by: Eddie Ringle <eddie@eringle.net>
Introduce turfs_virtual_path()

Signed-off-by: Eddie Ringle <eddie@eringle.net>
Introduce turfs_resolve_path() and implement on OS X

Signed-off-by: Eddie Ringle <eddie@eringle.net>