Patch looks good, closed.

Moritz looked into this in r4384.
Needs a second pair of eyes, and then we might close this bug.

The preprocessor removes dominated transitions from DTGs, but this does not take
action costs into account. The definition of dominance should be adjusted in
such a way that a more expensive transition cannot dominate a cheaper transition.

Maybe wait with this until the preprocessor is folded into the search code.