Make Time-Reverse Keyframes work for non continuous selected keyframes

[Jaydude-wb]

Time-Reverse Keyframes seems to ignore any keyframes selected between the firs and the last selected keyframe.

Came across this, while I wanted to create an alternating color transition (see picture for the situation).

I selected every other keyframe, but invoking Time-Reverse Keyframes just reversed the whole keyframe sequence, ignoring my carefully selected subset.

Please make the function work for selections as well.