Selecting Display to Show wvkbd on

[snyball]

Hi! This project is really useful for using a laptop connected to a TV with only a mouse, but I don't see a way to select the display that wvkbd is shown on. I suggest adding this as a new command-line option.

[proycon]

I agree. Though the command-line option is not implemented yet, the above patch by @mojyack ensures it starts starts on the current display rather than always on the first one.