fixed recognition cmake file and added ransac_based recognition headers at old locations which include the headers at the new locations and deprecation warnings.
CMake changes were not included in previous commit.  Now they are
recognition/CMakeLists.txt now installs the old header files along side the new ones.  Only the new header files were installed in the previous commit
uncommented old implementation files includes in recognition/CMakeLists.txt
ransac_based/ was missing from path to old headers causing error in cmake.  Fixed it.
update covariances only if a new pointcloud was set

this avoids unnecessary recalculations if only one of the pointclouds has been changed
Added missing PCL_EXPORTS macro to pcl::on_nurbs::FittingCylinder to allow linking.
Fix for issue #284 - just needed eigen align macro
Fix: only left button press event was invoked
Add: ability for user to set its own interactor style
Fix: addRectangle as of VTK 5.8 handling y coordinates
Revert "Fix: prevent usage of qt5"

This reverts commit d6455a25731af2bae835408b833c5b2ff40f3626.