Major update version 0.15
    MainWindow class:
        now images names show in application title
    NavigationViewer class:
        added navigation bars
    Image class:
        improved and fix code
    ImageManager class:
        fix image events (change/create/delete/rename)
        fix cache management
    ImageViewer class:
        resize policy events used as expected
        improved scale increasing method
        callbacks for resize policy events
        now can show NavigationViewer instances
    LinuxWatcher class:
        changed logic of detecting modifying and creating file
    Total:
        removed unused files
        some bug fix