Insert comments into PS, EPS, and SVG exports for paths.

Place markers in the exported vector graphics files marking
where paths are. This makes it easier to track down what
path is being drawn.

Change-Id: Id8582cc2bcb33c2afca6db545f4048c3b8ad1ad0
Add a setting for GL2PS export of painter renderings.

Change-Id: I7783f1c7d3cb58ec5f53c6b28ce6970f9034cd54
Fix issue introduced by cell iterator refactor.

The IsValid() method was changed to IsDoneWithTraversal(), reversing
the logic of the method. However, the implementations/usages weren't
reversed.

Change-Id: I825616564d79cacc81a688b5fd9b04c9c7a15d8d
Add a pointer check in vtkPolyData::ShallowCopy to avoid a crash

Change-Id: I0afe81b00ac92cbcf7455a54b9f3e142f17cb6ec
Merge topic 'fix-celliterator-usage' into master

4ba6f4cc Fix issue introduced by cell iterator refactor.
Merge topic 'add-check-vtkPolyData-ShallowCopy' into master

12762865 Add a pointer check in vtkPolyData::ShallowCopy to avoid a crash
Merge topic 'gl2ps-presets' into master

13c6f1ca Add a setting for GL2PS export of painter renderings.
bcf03bc8 Insert comments into PS, EPS, and SVG exports for paths.