Fix GNU LGPL licensing

According to what I see and what https://www.gnu.org/licenses/gpl-howto.html requires, a "Lesser" is missing in most cases.

This commit is the result of running:

    find * -type f | grep -v -e '^COPYING$' -e '^waf$' -e '.xpi$' |
    while read f ; do
      mode=$(stat -f %p "$f")
      sed 's/General Public License/Lesser General Public License/g' "$f" > "$f.222"
      sed 's/Lesser Lesser General Public License/Lesser General Public License/g' "$f.222" > "$f"
      rm "$f.222"
      chmod "$mode" "$f"
    done