VTK6 cmake fixes
VTK6 code fixes. VTK5 backward compatibility
Fixes VTK's definition bleed in PCL_DEFINITIONS
Fixes out of core test with VTK6, overlapping namespaces
Merge pull request #363 from fran6co/vtk6-fixes

[Rebase] Make fixes for VTK 6
Only install advanced tutorials if they where acutally generated
Merge pull request #701 from jspricke/fix_advanced_tutorials_install

Only install advanced tutorials if they where acutally generated