Refactor MainWindow::initializeUI()
Modification Indicator [resolves #26]

Show indicator in window title when the markdown document was modified.
Save Changes dialog before opening a file [resolves #27]

Ask user if modified markdown document should be saved before opening
another file using File->Open or Recent Files menu.
Reorder methods in mainwindow.cpp based on header
Split initializeUi() in setupUi() & initializeApp()
Window Size, Position & State [resolves #14]

Save and restore the size, position and state of the main application
window.