Include CUDA and latex files in copyright check

Include CUDA and latex files in copyright check

Now also CUDA and latex files are indicated by the .gitattributes file
to contain copyright, and the copyright.py script can deal with them.
This should conclude the work to reformat copyright headers in the
master branch.  Some individual files may still be missing, but those
can be fixed when spotted.

Part of #818

Change-Id: Ib6d3e10b57a42ea7a8c990e51df669cace4c8d8f