Re: names of vertical spacing dimensions

[Mark Polesky]

IIUC, making all of these changes should be done in 5 steps:

1) rename the variables in the code files
2) change 'space to 'default-distance* in the code files
3) write rules for convert-ly
4) update affected regtests (?)
5) update the docs

*or Alexander's "optimal-distance" (still open to debate)

Does these 5 steps sound right?

If so, I'm probably able to do #1 and #4, and definitely
able to do #5.  If I tried to do #2 and #3, I'm pretty sure
they would take me way too long and I'd probably mess them
up anyway.  I *think* I've taken care of #1.  Here's a
patch:

http://codereview.appspot.com/2303044

Please double-check this to see if I've missed anything
(more than likely, since C++ is largely foreign to me).
Once this patch is approved, maybe Joe can then change
'space to 'default-distance*, and we can go from there.

*or Alexander's "optimal-distance"

Thanks!
- Mark