* DevilImageReader renders into ImageDataRenderTarget (intermediate solution...)
 * further work on IxpvDemo pipeline
 * RenderTargetCompositor knows difference compositing

git-svn-id: https://camplinux.in.tum.de/svn/campvis/trunk@389 bb408c1c-ae56-11e1-83d9-df6b3e0c105e