data: refreshing with DB

* database stores modification time of files.
* FileManager updates internal state based on database info.
* reimplemented FileManager's check if a file is in project.
* implemented clearing data of updated or removed files before reparsing the updated and added files.

src/lib/Application.h

@@ -28,7 +28,7 @@ public:
 	~Application();
 
 	void loadProject(const FilePath& projectSettingsFilePath);
-	void reloadProject();
+	void refreshProject();
 	void saveProject(const FilePath& projectSettingsFilePath);
 
 private: