Fixed VTKCell being used as port even if spreadsheet is not loaded
Fixed VTKCell being used as port even if spreadsheet is not loaded

With the new constant spec there is no way of making
this dynamic, so we replace the type with a Variant.

Now that we do not allow modules on ports,
should port types really be modules?

Fixes #1030

VisTrails/VisTrails,hjanime/VisTrails,hjanime/VisTrails,minesense/VisTrails,minesense/VisTrails,VisTrails/VisTrails,VisTrails/VisTrails,VisTrails/VisTrails,hjanime/VisTrails,minesense/VisTrails,hjanime/VisTrails,VisTrails/VisTrails,minesense/VisTrails,minesense/VisTrails,hjanime/VisTrails