Read the right .gmo files when running in place

Read the right .gmo files when running in place

With gettext, we have been forced to install .mo files at the right place in order to read them. Now that we have our code, the situation changes.

* Add new method Package::messages_file(code), when returns the right path, depending on whether we are running in place.
* In Messages class use that intead of the existing one.