Morphing dice now do not morph after unsuccessful trip attack

Fixes #802.

This fixes the longstanding bug that morphing dice were morphing after an unsuccessful trip attack, instead of on capture, which is what was intended.

http://jenkins.buttonweavers.com:8080/job/buttonmen-blackshadowshade/453/
Just so you know, there's no need for this kind of logic in tests any more --- any time you want in a test, you can define:
```
  global $BM_RAND_VALS;
  $BM_RAND_VALS = array(3, 17);
```

and the next two die rolls will come up 3 and 17, then the die roller will go back to being random.  The responder tests blow up if you don't define all of the random numbers, but that's a conscious decision to set `$BM_RAND_REQUIRE_OVERRIDE = TRUE;` in those tests.  If you just want a couple of non-random values at a particular time to cause a particular outcome, the formulation above should Just Work.