Set the title of a window from the command line.

Usage:
    set-window-title [-id window-id] [-r] new-title

Requires `xwit` and `xprop` to be installed. `xwit` could probably be made
unnecessary.

If -id is not given, will prompt to select a window by clicking on it. This
requires `xwininfo`.

After using this, `xwininfo` will report windows as having no name. I'm not sure
why. `xprop` appears to report everything correctly.