showing development of campus over time

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

bmg'ers,

if we had a year of construction associated with every
building on campus, we could add a few cool capabilities
to the walkthrough application:

  1) displaying each building's construction date near
  the building, or upon selection of the building

  2) displaying the appearance of campus as of a
  particular year

so, for example we could move a slider and show various
buildings appearing on campus in the order in which they
were constructed.

michael, peter, can you think about how to incorporate
this info into the pipeline (perhaps with a fetchable
"year of construction" datum from the DOF web site, to
be supplied initially by us), how to propagate it downstream,
and how to use it in the viewers?

seth.