Improve the validity view

This contribution uses forms and manages actions:

- to run the validation on a opened model
- lock the validation on the current opened model
- filter the validation results (failures, errors, infos and warnings)
- show/hide unused nodes
- select/deselect all nodes
- select/deselect directly defined constraints on nodes
- add markers for model navigation
- add markers for constraints navigation, etc.


Change-Id: I130afba4fcc55d754f4720fce08f66f67ef4da93
Signed-off-by: marwa rostren <mrostren@obeo.fr>
Enable Validation Results Export

This contribution adds a new extention point to permit a user defined
exporter. Two exporters ar suggested by default (Text and Html). And an
export action is added to the validityView.

Change-Id: I7e96e7197f0e2984c241dcfe8db91441cdb764b7
Signed-off-by: marwa rostren <mrostren@obeo.fr>
Rename plugins

plugins was: 
- org.eclipse.emf.* instead of org.eclipse.ocl.examples.emf.*
- org.eclispe.ocl.examples.* instead of
org.eclipse.ocl.examples.validity.*


Change-Id: I6e85042bb21321e0cad3f4fd0a6d505bc1851597
Signed-off-by: marwa rostren <mrostren@obeo.fr>