renderer-mesh: fixed bug in getBoundingBox()

It might be the case that the renderObject is not yet created and also
that the renderObject is present, but not the mesh itself.

Added some checks.
tests-scenegraph: added bbox test that covers the just fixed behavior
Merge branch 'meshbbox-bugfix' into develop
Fixed handling of mimetypes in resource manager. Mimetypes like "text/xml; charset=UTF-8" were being
improperly ignored
Stop propagation for all events emitted on canvas

Currently this breaks the camera script.
Added mouseover handler that triggers a mouseover event for the xml3d element
Improved (shortend) event registration on canvas
Changed parameter name of event attribute to 'event'

Though there is no reliable way to get the event as parameter from event attributes, using 'event' seems the most common way. At least this works in FF and Chrome.
Made available canvas events global.
Moved xml3d::processListerner, group::processListener and mesh::processListener into on method in RenderAdapter

Is called initializeEventAttributes now.
Bugfix in mouseover/out logic
Towards clean code

Adapted tests to new interface
Initial version for touch support

Made event types plugable
Moved mouse event handling to a separate module
Removed some debug output
Fixed bug
Merge branch 'touch-events' into develop
Added a null transition to the state machine to cover the case where a material is updated
before lights have been processed.
Added data interface to SinkElements
Fix for correct touch event handling

Signed-off-by: Juergen Grueninger <juergen.grueninger@dfki.de>