Partitura Magica Code2

moved PlayerViewDX into main project
this version displays the lines correctly,
but it takes too long to load the view
no navigation yet

this version scrolls smoothly

first version using direct3d

some experimental dx views

slightly improved the menu

reviewed todo prios and impl. selecting of nearest box
after removing a box

bugfix: play shall not be started if no box exists

clean separation of ClosePartituraCommand and CloseApplicationCommand
bugfix: now using the wpf specific common dialogs instead of windows forms

new extension method CommandExtensions.TryExecute()