DXDocumentViewerView no longer used in c.documentviewer 5.x

An import to DXDocumentViewerView from c.documentviewer is in overrides.py. The class is no longer in version 5.x of the module so an import error occurs.

Also, the template for the override is no longer in the source code:

Start in overrides.py and inspect the import of DXDocumentViewerView from c.documentviewer, then compare it with the version 5.x API. Review the shown collective.documentviewer ZCML override and its templates/documentviewerdx.pt reference. Done means the import error and obsolete template override no longer affect use with c.documentviewer 5.x.

Written by the indexing model from the issue text.