This commit introduces REUSE compliance by annotating all files
with SPDX information and placing the reused licences in the
LICENSES folder.
We additionally removed the docheader tool which is made obsolete
by this change.
The main LICENSE and copyright text of the project is now not under
my personal name anymore, and it belongs to "The Respect Project
Contributors" instead.
This change restores author names to several files, giving the
appropriate attribution for contributions.
With this change, we won't need to change the `PostalCode` validator
every time there's an update. While I was moving the data, I noticed
some inefficiencies with the regular expressions, so I made some
changes.
