[LDView] Simplified boxes

[Michael Horvath]

I tested, and it does appear that LDView is detecting the boxes as parts. So, my guess is that LDView spends more time traversing the parts in the model than it does drawing the geometry for each part.

I have also "inlined" my town MPD model to the "library level" using MPDCenter. This should have reduced the number of branches on the model tree to 1. I assumed this would produce a big performance boost, but it hasn't. Oh well. Kind of defeats the whole purpose of taking these steps and creating LDBoxer.