applied changes from email

included 2 new assets for interface
and 3 new 'symbolic' assets as placeholder
(herz, heart, brush). applied code changes
in launch state (loading) and barn state
(using)
Merge branch 'master' into feature/interface-manager
asset overhaul and scene graph

rearranged assets in subdirectories. rendering
is now done via a scene graph, see ISceneElement
for further information.