Changed proxy settings
XTKViewer is loading a dummy curtain as overlay to the volumetric data
Added multi-group obj support for XTKViewer
K3D.parse.toIndividualOJBs: generalized to support objects and groups
added example to show the final dummy curtain format within the XTKViewer
removed test files
Adapted config.json settings to development settings
Merge branch 'master' into fha-next
added (untested!) functionality to display a multi-part response to a W3DS 'model/obj' request in the XTKViewer

THIS COMMIT IS NOT FUNCTIONAL, IT USES NON GRAPHICAL TESTDATA ONLY
support for visualizing multiple volumes out of a multipart response is working now
Moved generic functionality from 'VirtualGlobeView' to 'BaseView'
Moved generic functionality to BaseView and adapted VGV and RBV viewers
Added two new volumetric data-sets to config (ALARO)
Adapted SliceViewer to new layer infrastructure
Corrected small typos in config
added correct removal of volumes. there are some edgecases still to be fixed...
Fix for VGV to only display W3DS layers of type 'vertical_curtain' and added back color-ramp rendering for vertical curtains
Added new layer for testing in config and solved problem of only one gui element appearing on multipart response of various volumes
Another fix for layer management in SliceViewer
Recenter SliceView after all volumes were deleted