Updated stuff, read desc.

Removed modularity folder, to follow the structure for blocks and items,
modules are in a "module" folder.
Added french translation.
Removed the method that returns the next available ID, the module IDs
can be changed manually in config anyway. The good thing about this is
that now the id is hardcoded (until it's in config), we can register all
the modules in the Registry class again.
Moved a lot of code from ConfigFile to the new Modules class