Allow binding to key release

[Toesmasher]

Key bindings currently take action once a key is pressed down. This is a sensible default for the overwhelming amount of cases, however there are use cases for binding to when keys are released as well, and I currently find myself wishing I could mute my microphone by holding down a key and unmute it when the key is released.

Rough idea:

binds {
  M repeat=false { spawn "wpctl" "set-mute" "@DEFAULT_AUDIO_SOURCE@" "true" }
  M release=true { spawn "wpctl" "set-mute" "@DEFAULT_AUDIO_SOURCE@" "false" }
}

Binding to M is obviously silly, but it should demonstrate the idea. The fact that repeat=true is the default for keybindings does throw a wrinkle in here, though.

[YaLTeR]

This is gonna happen at some point, it's just nontrivial input logic that needs to be both written and well tested.

[bphenriques]

This might be interesting to temporarily show the status bar as well. I personally keep it off most times and toggle it on demand