Add support for Melange model adaptation (wrt model conversion)

When dealing with multiples compatible languages (for ex. inheritance), GEMOC currently supports **model conversion** through the use of the URI of type `melange:///lang=` (see http://melange.inria.fr/documentation/)

This is used in the current official sample FSM.

However, Melange is supposed to be able to support **model adaptation** using URI of type `melange:///mt=`

Using one or the other of these approach has pro and cons, especially it has has impacts on how to implement the animators.
typically: which ecore is used has base for the animator ? (MT or generated runtime language).

Additionally *adaption* is supposed to be enable the reuse of existing code (for example a big validation code written in java that we want to directly reuse in the execution semantic of the extended language )

when running a model and depending on the animator implementation we should select one or the other URI (or propose the choice to the end user).

At some point, the animator implementation should declare which kind of melange query it supports.