List lister helper

I have not tested this code yet because of how the develop branch is not yet in a usable state, but as I may be missing for a few days I thought I should get it here in case you want to give it a try.

To use:
```
LIST PARTS IN FOO.
PRINT FOO. // terse
PRINT FOO:DUMP(). // verbose
```

I didn't actually expect anyone to have something nested that deep, but I started getting worried about what would happen if someone decides to dump the contents of a structure that contains a reference pointing back to itself, and thus the full-depth print gets stuck in an infinite loop.  The 99 was just there to prevent it from locking up all of KSP if that happens, but still leave it being annoying enough that someone will notice and want to stop doing that.