Add menu entry to register EMF metamodel

[RolandKluge]

Similar to
http://www.kermeta.org/docs/html.chunked/KerMeta-Deploying-a-code/ch04.html
https://eclipse.org/epsilon/doc/articles/reflective-emf-tutorial/

Helpful code in Epsilon:
https://www.eclipse.org/epsilon/download/
plugins/org.eclipse.epsilon.emf.dt
class: org.eclipse.epsilon.emf.dt.RegisterMetamodelAction

[anthonyanjorin]

Hmm... so we want to offer such functionality ourselves? Why not just install and use the plugin from kermeta?

[RolandKluge]

This is true if we expect that we only need to register EPackages seldomly.

However, we may expect that, in the near future, eMoflon and Henshin will have more and more connection points, and Henshin sometimes requires to register EPackages (but offers no convenient menu entry for this, as far as I know). Therefore, I think that it's better if we ship this tiny feature with eMoflon instead of forcing people to install Kermeta (or Epsilon) for just this purpose.

[anthonyanjorin]

I agree! And we can do it better too. For example we could add an option: "Automatically repeat this registration every time I start Eclipse", offering preferences where this of course can be changed later. Kermeta is nice but reregistering the same metamodels 100 times was still a *** in the *** :)

[RolandKluge]

For the moment, I simply allow for registering the metamodel once. We do not save the list of registered metamodels.
If this is a requirement, please open a separate issue and I will implement it (Epsilon already provides this features but using a deprecated UI API).