[yt-dev] Finalizing the license switch

[Matthew Turk]

Hi everyone,

I'm writing about the licensing situation.  A while back we had a
discussion about transitioning to BSD 3-clause.  Here is the progress
on that:

 * I have received (offline or online) consent from everyone listed on
the spreadsheet.
 * The ARTIO headers in yt-3.0 will be licensed under the LGPL, which
we will note in a file at the top level.
 * Kacper has moved in the main yt repository all of the external
dependencies to an extern/ directory.  This also isolates some of the
LGPL code.
 * The rockstar wrapping code will need to be removed before
relicensing can occur.  (I believe -- Rockstar itself is GPL.)  I have
created a fork of Rockstar's source code that will bundle the yt
interface.
 * Everyone has consented to the shared copyright model, similar to
what IPython does.
 * One or two additional people have contributed since my initial
spreadsheet was made, and I am tracking them down presently.

Unless I hear any objections, I will issue pull requests to both 2.x
and 3.0 that:

 * Remove the Rockstar wrapping code
 * Removes the GPLv3 license, replacing with 3-clause BSD
 * Removes all attributions that include affiliations and replaces
with a collective copyright header, similar to what IPython does:
http://ipython.org/ipython-doc/dev/about/license_and_copyright.html  I
am still not sure if we want authors listed in individual files, but I
am certain we do not want the full author/affiliation/years/copyright.
 * Include the copyright information at the top level of the source repository
 * Notes that the ExtJS code itself is GPL, but we do not "link"
against it directly in the code shipped in the yt source distribution,
instead using a <script> tag to include it in an HTML file.

I will also update the website and documentation to note the change in
license and write a blog post summarizing the discussion.  We may also
want to issue a point release just for the change in license, although
I would prefer to issue a 2.6 at some point with the license change.

I'm going to begin preparing this potentially as early as today, but
the pull request will not need to be accepted immediately; it can
wait, and perhaps even be rejected depending on discussion.

Best wishes,

Matt