detect emfruntime desynchronisation and propose to regenerate

[dvojtise]

currently the Emfruntime (ecore+project) is generated on request only via a quickfix (because it take too long to be done on the fly in the xtend) As it is generated only once, it may be desynchronized with the actual source ecore+aspect.

we need to first detect such desynchronization and second propose a way to regenerate the ecore, genmodel and code.

for the detection we may use an EMF compare. this should be done either in the validate phase of the xtend compilation. Or if this is too time consumming need to be added in a new builder that would host long running tasks. once detected it may be reported as an error or warning as a support for quickfix that propose to resynch This resynch action should also be proposed as a popup action (right click on metamodel)