Mark In & Mark out Dissolve marks are carried over to next clip

Turns out the fix was not easy to move from v1.5.4 to v1.5.3

The good news is, we stamped an official v1.5.4 release today, and we also added the fix for the other issue Peter found.

Please update to v1.5.4 b5463 if you are having this issue.

/cc @joeral