command: fix video-rotate update when paused

Due to the way video-rotate currently works, the state will be
automatically updated once new video is decoded. So the filter chain
doesn't need to be reinitialized automatically, but there is a need to
trigger the video instant refresh code path instead.

Also move the support function closer to an annoying similar yet
different function. They probably can be unified next time major changes
are done to this code.
command: make reverse cycle_values match up with forward one

The behavior of reverse cycling (with the "!reverse" magic value) was a
bit weird and acted with a "delay". This was because the command set the
value the _next_ command should use. Change this and make each command
invocation select and use the next command directly. This requires an
"uninitialized" special index in the counter, but that is no problem at
all.