Now whole Magnum, Magnum::SceneGraph and Magnum::Math namespaces are
fully documented -- each class has at least "getting started"
documentation, larger modules are documented on separate pages.
Using header with forward declarations, containing declarations for all
classes with default parameters. The classes themselves don't have the
defaults.
This also allows users to more conveniently forward-declare instead of
digging in sources and writing the declarations on their own.
* Camera is now templated also on underlying floating-point type.
* Drawable objects can be split into groups (e.g. for separated
rendering of transparent objects)
* Added (long time missing) test for draw() function.