Improvements in the documentation.

In particular, we use list-tables now instead of real tables, making it
easier to update the table's contents in case we ever need to.
Add missing empty line after admonitions.
Update submodules.
Update the code for compatibility with Plop 1.x.y.

Also update copyright information.
Update translation template.
Add copyright information.
Update config validation schema.

Take into account the fact that Plop 1.x.y no longer provides any means of
configuration by itself and so does not provide a validation scheme anymore
either.
Update DIC config file for Plop 1.x.y.
Delete old SQL script that was never used.
Alpha integration of composer.

Also clean up some bits related to packaging.
Merge branch 'master' of github.com:Erebot/Erebot