make progress stop when block stops

[grosser]

replaces #203

@zdrve

[zdrve]

It's not as watertight as my PR, but it'll help most of the time, I'll give you that.

Edit: mine has the same bug. It's fixable in mine; not sure it is in yours.

[grosser]

I'm not aware of any edge-case or bug that is not addressed, can you elaborate ?

[zdrve]

         break if stop
                         # <- the other thread calls 'thread.run' here
          Kennel.err.print animation[count % animation.size]
                         # <- or here
          sleep interval

in which case the .run won't wake up the thread, because it hasn't slept yet.

[grosser]

yeah true, good catch :)
0.0x% chance that we lose 0.2s so should be fine :)

[grosser]

found 1 more race condition that could crash the progress #205