gta02-core license

[Werner Almesberger]

We haven't specified a license for the gta02-core work yet. Let's do
this now. Following the licenses Openmoko uses, I'd propose:

- for code that's not a library, GPL >= 2.0
  http://www.gnu.org/licenses/gpl-2.0.html

- for code that is likely to have uses as a library per se,
  LGPL >= 2.1
  http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html

- for non-code, which will be the bulk of the work specific to
  gta02-core, CC-BY-SA 3.0
  http://creativecommons.org/licenses/by-sa/3.0/
  http://creativecommons.org/licenses/by-sa/3.0/legalcode

The overall goal being to maximize compatibility with projects similar
in spirit (hence no GPLv3) and requiring a basic quid pro quo (hence
GPL and by-sa, not BSD or public domain).

- Werner