Script to automatically update copyright

Adapt the automatic uncrustification script to also update the
copyright header for changed files.  Add a Python script to do the
actual copyright header processing.  The Python script can also do other
copyright header tasks.  Make the pre-commit hook more flexible to be
able to do either only uncrustify or only copyright checking, as well as
temporarily skipping the hook for a commit.

Related to #818.

Change-Id: Ie21365acbe07e1f097e6d72c6a5e0d0826631ff0