Fix FSF address in headers and license file

[mattiaverga]

Some headers and the liblilxml license file still report the outdated Free Software Foundation address.

[brandon-rhodes]

According to the Fedora project, the license itself can't be changed:

https://fedoraproject.org/wiki/Common_Rpmlint_issues#incorrect-fsf-address

Could you remove the LICENSE file from the pull request so we avoid rewriting a license that isn't ours to rewrite? Thanks! (Or, am I mis-applying the Fedora rule?)

[mattiaverga]

mmm I assume we can overwrite the LICENSE file with an updated copy from FSF, I don't think it changes anything but the address.
But I'll ask on Fedora legal mailing list for clarification about that.

[mattiaverga]

So, it doesn't seem important to update the FSF address, after all... https://lists.fedoraproject.org/archives/list/legal@lists.fedoraproject.org/thread/4N3NO5NJJ6ND3T2ZDZ2A6LF4HRBOTWVR/

I'll update the PR to only change the FSF address on xephem sources, leaving the liblilxml sources untouched.