Support arbitrary window sizes

[ghost]

Use case: Some people may want to fit window sizes to certain images, or to fit the window to ridiculously small monitors.

Desired behavior: Be able to specify a starting resolution either with program arguments or with JVN-DP script

Current Workaround: None

Suggested workflow for issue assignee: All of the things that draw window elements typically have x, y, width, and height arguments. Since these are already scaled to the default 800x600 resolution, you could get the ratio of the new screen resolution width and height to the old ones and scale according to that.