Cleanup OggTheora support.

There was no way to know if vtkIOMovie had OggTheora support enabled. Hence
adding a vtkIOMovieConfigure file that has this configuration made available.
Now when OggTheora support is available, vtkIOMovieConfigure.h defines
VTK_HAS_OGGTHEORA_SUPPORT.

Change-Id: I1efe54cb43f3ea09ab36a7bfa5a6a13d9b5c0593
BUG #14086: Fix vtkImageAppend when no active scalars are present.

vtkImageAppend failed when the image data didn't have any point-arrays marked as
scalars. Though vtkImageAppend's execution handled that case correctly, the
initialization did not. This patch fixes the initialization code.

Change-Id: I9207646b13038a96a26051fc3aed6d554a55aaf3
Merge branch 'fix-image-append-rel' into release

Change-Id: I8233c8cbb425523d774d32032956e767b64524a5