make `reverse` a "power window button" (like effect toggles)

[ronso0]

Feature Description

Like the effect toggles:

• latch on click
• enable on longpress, revert on release

When I want to play with reverse it's a bit annoying that I have to keep revert pressed pressed while I actually want to do other stuff (effects, transitions, ..).

IMHO making this a power window button wouldn't change UX in most cases, except reverse is used for nudging the track (i.e. for beat-matching), and it that case toggling Play off & on again would achieve the same.

Some refactoring would be required, e.g. reject / reset reverse if not we're not playing and no track is loaded.

Same applies to reverseroll.

[ronso0]

Or shall we add a new control reverse_play that basically toggles play (play_latched) and reverse?

[Swiftb0y]

Regardless of the implementation, the reverse CO itself should not be changed as that would be a break in API.