Improve Qml code model import handling.

* Fill the snapshot with files that could be imported.
* Implement package imports.

* The qmldir file is not parsed yet.

Reviewed-by: Erik Verbruggen

src/plugins/qmlprojectmanager/qmlproject.h

@@ -106,6 +106,7 @@ public:
 private slots:
     void refreshProjectFile();
     void refreshFiles();
+    void refreshImportPaths();
 
 protected:
     bool fromMap(const QVariantMap &map);