Feature: toggle hydra hint window

[klephron]

Example use case:

1. Press hydra body or body + head, now hint window is visible
2. Execute cmd to toggle hydra window, hydra is still active but the window is hidden
3. Execute cmd to make hydra window visible again

For example, it would be nice to use with dap or git

[anuvyklack]

Nice idea. I will do it, but not now.

[WillEhrendreich]

I was wondering about this, I want the option to hide it too. I guess I have to go with a different kind of hint display for now.