In addition to 37e4f9d6f7 which did the
change for Sdl2Application (because Emscripten required it), making sure
that everything (except GLUT, which does it by default) behaves the
same.
Moreover, some applications don't expect viewport size changes at all
(e.g. the app can't change size of immutable texture used for rendering)
and thus the original way to defer the initialization until
viewportEvent() is called would be overly complicated.
Also, since framebuffer classes store viewport size in them, there is no
need to call viewportEvent() on initialization. The current ways to do
the initial call in Sdl2Application, *XApplication and NaClApplication
were nothing more than ugly workarounds for mimicking GLUT behavior,
which is bad.
Lastly, to be sure that nothing breaks in user apps, I did this change
in magnum-bootstrap long ago and all bootstrap application behave the
right way.
Each implementation of *Application::Configuration will have different
methods tailored to feature set of the underlying toolkit. Currently
each windowed application's Configuration has only window title (except
NaClApplication) and window size. WindowlessGlxApplication has empty
class. More features will come later. Also created introductionary
documentation for Platform namespace.
Apparently input events can be processed during buffer swapping. Now
asserting that callback from buffer swap is not called during input
event processing (which shouldn't, as both functions should be called in
the same thread).
NaCl and SDL2 are now hotswappable again without any unimplemented or
superfluous function parameters.
Also added missing EnumSet operators for Modifiers.