Added missing NULL checks before accessing GetInteractor().
Errors are now reported using Message::SendFail().
Not found actor names are now reported as syntax error instead of silently skipping them.
ivtkinit now accepts aguments -srgb and -msaa for overriding defaults.
Default MSAA settings have been changed from 8 to 0 to match vinit behavior.
Added command ivtkclose closing a Vtk view.
Added commands ivtkaxo, ivtkfront, ivtkback, ivtkleft, ivtkright,
ivtktop and ivtkbottom assigning view projection similar to sonamed commands in ViewerTest.
Added commands ivtksetcolor and ivtksettransparency assigning
color properties to shaded presentation.
