Moved OGS_BUILD_GUI test up in order to have the switch OGS_BUILD_GUI in all parts of OGS source code.
Using GEOModels object from ProjectData object.
Added libVtkVis and libQtDataView for linking in OGS_BUILD_GUI mode.
Linker fix in testrunner when OGS_BUILD_GUI=ON
Switched sequence of linked libs.
Merge pull request #257 from TomFischer/GEOModelsGUIBugFix

Bug fix for GUI