Make ZKL remember previous window size & location and restore it upon restart.
Config.cs: store location & size
MainWindow.cs: save position & size when closed and reload them when Initialized.
Program.cs: relocate the check-desktop-size-and-downsize-window-if-not-enough-space code to MainWindow.cs
Merge pull request #38 from xponen/remember_size

Make ZKL remember previous window size & location and restore it upon restart