[Feature Request] Set Default Window Size

[TheKins]

I typically play old games in a window and prefer to have them at a typical resolution (usually either 1280x720 or 1600x900) so that it still fits nicely in a OBS 16:9 stream window. By default, OpenJKDF2's window resolution defaults to 640x480 and you then have to set the size manually (and probably messily!) by dragging the window borders.

It'd be nice to be able to set a different default window size, even if only via command line.

Also: Thanks for the source port! It's very good, and sorely needed. :)