qmljs: better defaults, more uniform handling of paths

Uniform handling of the different qml dialects.

Now paths for a given document prefer the project of that document.

For Qt the following sequence is used:
- Qt of the project of the document
- Qt of the active target
- Qt used to run creator

Currently all paths of the open projects are still merged, but that
can be changed.

Change-Id: Id302c13c893b66fbfe24e301602fe69de152eed4
Reviewed-by: Thomas Hartmann <Thomas.Hartmann@digia.com>

src/plugins/qmljseditor/qmljsfindreferences.cpp

@@ -831,7 +831,7 @@ static void find_helper(QFutureInterface<FindReferences::Usage> &future,
 
     QmlJS::ModelManagerInterface *modelManager = QmlJS::ModelManagerInterface::instance();
 
-    Link link(snapshot, modelManager->defaultVContext(), modelManager->builtins(doc));
+    Link link(snapshot, modelManager->defaultVContext(doc->language(), doc), modelManager->builtins(doc));
     ContextPtr context = link();
 
     ScopeChain scopeChain(doc, context);

src/plugins/qmljseditor/qmljssemanticinfoupdater.cpp

@@ -122,7 +122,7 @@ QmlJSTools::SemanticInfo SemanticInfoUpdater::makeNewSemanticInfo(const QmlJS::D
 
     ModelManagerInterface *modelManager = ModelManagerInterface::instance();
 
-    Link link(semanticInfo.snapshot, modelManager->defaultVContext(), modelManager->builtins(doc));
+    Link link(semanticInfo.snapshot, modelManager->defaultVContext(doc->language(), doc), modelManager->builtins(doc));
     semanticInfo.context = link(doc, &semanticInfo.semanticMessages);
 
     ScopeChain *scopeChain = new ScopeChain(doc, semanticInfo.context);

src/plugins/qmljseditor/qmltaskmanager.cpp

@@ -161,7 +161,7 @@ void QmlTaskManager::updateMessagesNow(bool updateSemantic)
     QFuture<FileErrorMessages> future =
             QtConcurrent::run<FileErrorMessages>(
                 &collectMessages, modelManager->newestSnapshot(), modelManager->projectInfos(),
-                modelManager->defaultVContext(), updateSemantic);
+                modelManager->defaultVContext(Language::Unknown), updateSemantic);
     m_messageCollector.setFuture(future);
 }