add methods for removing hotkeys and hotstrings

[spyoungtech]

Resolves #213

Adds new methods for removing hotstrings/hotkeys:

• remove_hotkey to remove a hotkey by keyname
• clear_hotkeys to remove all hotkeys
• remove_hotstring to remove a hotstring by trigger sequence
• clear_hotstrings to clear all hotstrings

Like adding hotkeys or hotstrings, using these methods while the hotkey process is already running causes a restart of the hotkey process.

---

During testing, a bug was discovered in which a race condition existed if you tried to stop hotkeys too soon after starting them. The dispatcher thread is responsible for creating the subprocess, but because this happens asynchronously it's not guaranteed that the subprocess has started by the time stop is called.

As a temporary fix for this bug, the stop process will wait up to 1 second for the process to exist.

[coveralls]

coverage: 75.079% (+0.4%) from 74.724% when pulling be53d46 on gh-213 into bf83a24 on main.

[nnako]

Hi @spyoungtech . Seems to work fine. I tried remove_hotkey() and clear_hotkeys(). the only thing is that an error is thrown when I try to remove a hotkey which I have not previously added. Would it be possible to rather ignore this? rather than throwing an error? ignoring it could result in a bit more usability, as the developer does not have to keep track of the hotkeys created by add_hotkey().