Rewrote texture managment (experimental)
Merge branch 'master' into v0.6-dev1

Recent changes are now also in private development branch.
Unified load functions
AnimatedPicture now works with index instead of id
Removed unneeded virtual functions
Finished documentation + added SeparateHoverImage option to more objects
Added MessageBox object
Replaced Window with Gui class
Made loadObjectsFromFile work again
Added getLoadedConfigFile function to objects
Made Form Builder work with recent changes
Fixed bug in loading bar with a changed minimum
Fixed bug in slider when calling setVerticalScroll after setSize
Set texture pointer to NULL when no longer in use
Fixed possible segfault on exit with VC++
Fixed bug in EditBox callbacks
Make sure all changes to master branch are also in testing branch
Fixed compilation issues
Remame file to make it clear that it can't be used
Removed union in Callback struct