(fixes VAOFileManager reloading every frame)

controllers for VAO, ShaderProgram, FBO now apply external attribute settings before merging in their own

Merge branch 'refactorGLobjects' of file:///data/git-repository/acgl/libraries/acgl into refactorGLobjects

* most members of RenderObject are now const (compatibility with resources loaded from FileManagers)

* VertexArrayObjectControl
* VertexArrayObjectControlFile
* ShaderProgramControlFiles
* FrameBufferObjectControl

* Buffer
* ShaderProgram
* VertexArrayObject

* uses GeometryDataControlFileFactory for loading
* should replace ArrayBufferControlFileATB

* remove debug outputs

* implement a more versatile PNM loading routine

Example:
SharedLocationMappings globalLocationMappings = SharedLocationMappings( new LocationMappings );
// now the map could get set by hand, but thats not needed:
ShaderProgramFileManager::the()->get( ShaderProgramControlFiles("shader1").
                                      externAttributeLocations(globalLocationMappings) );
// will add all maps from the shader1 to the global map
ShaderProgramFileManager::the()->get( ShaderProgramControlFiles("shader2").
                                      externAttributeLocations(globalLocationMappings) );
// will add all maps from shader2, attributes already known will not get changed, no location collitions.

Reloading of the shaders due to changed files will automatically set the locations again.