lod example with building.near, .medium, .far

[Seth Teller <teller@lcs.mit.edu>]

here's a concrete example of including 3
separate .iv files for building LODs

  http://city.lcs.mit.edu/bmg/lodexample.tar

each "building" is a simple shape with
associated label text.

all of the above is scoped under a single
transform (scale, rotate, translate) to
situate the building in campus coords.