Fixes#1803
Running a command that created a new screen would previously result in a screen
order that looked like this, due to how `Screen::Hide` works:
- DF screen
- `command-prompt` screen (dismissed)
- New screen
The `command-prompt` screen remained on the stack until the new screen was
dismissed, so it would intercept viewscreen vmethod calls intended for the
DF screen.
This change adds a new behavior to `Screen::Hide` that results in this screen
order after running a command:
- DF screen
- New screen
- `command-prompt` screen (dismissed) - DF removes this screen immediately