ProjectExplorer: Make Project::id value based

Change-Id: Ie210d2a068158c6caaac66aae58cbd886f61c18d
Reviewed-by: Tobias Hunger <tobias.hunger@digia.com>

src/plugins/qmlprojectmanager/qmlproject.cpp

@@ -110,6 +110,7 @@ QmlProject::QmlProject(Internal::Manager *manager, const QString &fileName)
       m_defaultImport(UnknownImport),
       m_modelManager(QmlJS::ModelManagerInterface::instance())
 {
+    setId("QmlProjectManager.QmlProject");
     setProjectContext(Context(QmlProjectManager::Constants::PROJECTCONTEXT));
     setProjectLanguages(Context(ProjectExplorer::Constants::LANG_QMLJS));
 
@@ -311,11 +312,6 @@ QString QmlProject::displayName() const
     return m_projectName;
 }
 
-Id QmlProject::id() const
-{
-    return "QmlProjectManager.QmlProject";
-}
-
 IDocument *QmlProject::document() const
 {
     return m_file;