[Sage] License info

[Alan Woodland]

A Debian user requested that sage be distributed within the Debian
archive. I've mostly made a package for this, but I have a question
about the licensing of Sage.

It's not clear what license sage is distributed under. If I had to take
a guess I'd say MPL/GPL dual licensed like most extensions on mozdev.org
seem to be, but none of the source files say this explicitly, and I
can't find it written anywhere else. I noticed there were several files
distributed under seperate licenses (e.g. sha1.js. which is BSD licensed.)

Could you please clarifiy the license of sage?

Thanks,
Alan