maintenance release

• add $metamodel.getMetaDef method,
• add $db.clear and $db.init methods,
• log a warning if the '_id' property of a component is changed during a $db.update,
• 'action' property of a behavior has now 'javascript' type,
• 'javascript' type is now part of monoco core system,
• changing the state of a destroyed component logs now a warning ($workflow is no more stopped),
• 'MonocoComponent' class has now the common APIs of a MonocoComponent class and
• update dev dependencies.