Add GNU Affero General Public License version 3

URL: https://www.gnu.org/licenses/agpl-3.0.txt
Last-Modified: Tue, 22 Jan 2008 19:36:14 GMT
Add copyright and license in the code
UTF-8 output
Show pointer to license in output
Fix unload of a previous angel when that angel has a different name
Use encoding from the local instead of hard-coded UTF-8

The encoding to use is now extracted from the locale instead of UTF-8
being hard-coded.
STDOUT and STDERR are now properly encoded with that encoding and @ARGV
is decoded before usage.
A warning is shown (if in diagnostics mode) if:
- the encoding has not been detected (locale issue)
- or the encoding is not an encoding of Unicode (UTF-.*) as some
  features will rely on Unicode characters for output (ex: analog clock).