#54 Added an option to open the main window maximized by default.

[Nano Anon]

Currently the program only restores the window geometry (size and position), or the fullscreen state when it starts, but not the maximized window state. There are already two open bug tickets about this: #118 and #130

I looked into this problem, and unfortunately the maximized state cannot be detected reliably, so it can't be saved into preferences and restored together with the window geometry.

My solution is to introduce a new option in the Preferences dialog to open the window maximized by default, similarly to the default fullscreen option.

[Oddegamra]

The program should now remember the maximized state, and hopefully automatically restore it without the need for a new preferences entry.