Shade: Overlay for loop hot cues

[daschuer]

Here the Shade version:

There is a unrelated issue to this PR that the button is not colored/Styled after setting the loop.

[ronso0]

Here's the hotcue button fix d4ffc38
WHotcueButton needs pixmaps for 3 states, that's it.

Please fixup/squash my suggestion above, then pick the fix. Feel free to merge yourself!

[daschuer]

Thank you, for help! Works perfectly now.