Merge pull request #27 from lat-lon/dragAndDropLayertree-191

Drag and drop layertree 191
Implemented layer aggregation in printing module. Disabled vector layer rendering.
Merge branch 'latlon-version' of github.com:lat-lon/geomajas into printingTimeoutFix
Fixed build error in printing module color correction
Refactored raster layer aggregation in printing component and mapmodel
Refactored ComboRasterLayerComponentImpl and separated buildAggregatedLayerList from rendering process in MapModel to prevent side effects.
Synchronize layer order with printing plugin
Merged latlon-version into printingTimeoutFix