Replace unicode license text with ASCII

Some license files were in unicode, which caused lice to crash with
input like `lice gpl3 >LICENSE` as the unicode would fail to decode to
ascii.

I have pulled the official ASCII versions of each affected license from
the official sites:

https://www.gnu.org/licenses/gpl-3.0.txt
https://www.gnu.org/licenses/lgpl-3.0.txt
https://www.mozilla.org/MPL/2.0/index.txt