Remove dates from the per-file copyright header

[exarkun]

Currently we include this header at the top of every file in Twisted:

# Copyright (c) 2001-2010 Twisted Matrix Laboratories.
# See LICENSE for details.

with only the dates varying, depending (sometimes) on when the file was introduced and when it was last modified.

The primary outcome of this is that most reviews start with the comment:

1. Please update the dates in the copyright header in modified files

This is strictly a waste of time for developers and reviewers.

The copyright header on all files should be changed to:

# Copyright (c) Twisted Matrix Laboratories.
# See LICENSE for details.

We should maintain a date only in the LICENSE file, and update it only at release times.

Various wiki and developer howtos should be updated to remove mentions of copyright date updates, as well.

[exarkun]

(In [30713]) Branching to 'consolidate-copyright-dates-4857'

[exarkun]

(In [30714]) Change the copyright headers with the rewrite-copyright-header.py script

refs #4857

[exarkun]

tool which did all of the header rewriting

[exarkun]

The branch has rewritten headers. All changes were made by the tool attached to the ticket.

[glyph]

Yes. Please. Let's land this and centralize all the copyright brouhaha. If anyone cares about dates of individual files, version control will always be there to tell them.

[exarkun]

(In [30752]) Rewrite the copyright headers to exclude date information.

Author: exarkun Reviewer: glyph Fixes: #4857

To avoid the need to perpetually update copyright dates in each file in Twisted, remove the dates from most files and just leave them in the LICENSE file.

As a side effect, some files also have had a trailing newline added where it was missing before.

[exarkun]

(In [31931]) Merge copyright-policy-5112

Author: exarkun Reviewer: ivank Fixes: #5112

Remove the recommendation to include the year in copyright headers, matching what we currently actually want to do with respect to these. See #4857.