Our copyright were were mostly correct, but we inconsistently used (C) instead of (c) like the rest of the CK code. This PR fixes that (using lowercase c) and adds a missing copyright header to one file.
* Add backward weight instance traits for xdl cshuffle.
To keep instance test file sizes reasonable, we start a new test_bwd_weight_instances_traits.cpp test file.
* Fix copyright notices.
* Remove (c) symbol, replace with (C).
Having UTF-8 in source caused an error with code generation.
