data: increased file clearing performance

This change passes all file node ids for clearing to the sqlite storage at once and makes use of ON DELETE CASCADE for
everything else, instead of manally deleting all source locations.

src/lib/data/SqliteStorage.h

@@ -40,8 +40,8 @@ public:
 
 	void removeElement(Id id);
 	void removeNameHierarchyElement(Id id);
-	void removeElementsWithLocationInFile(Id fileId);
 	void removeFile(Id id);
+	void removeFiles(const std::vector<Id>& fileIds);
 	void removeUnusedNameHierarchyElements();
 
 	StorageNode getFirstNode() const;