From Stephan Hunber, "I found some time and ported osgDB::FileUtils and DarwinUtils across new apis to fix the warnings about deprecated api-usage.

* osgDB::FileUtils uses now the Cocoa-API to determine the paths of the application-support-folder
* DarwinUtils uses now modern functions of the quartz-api to get and set screen-resolutions. Removed some of the osg-deprecated stuff.
"