[Halld-offline] BCAL geometry

[Beni Zihlmann]

Dear Coders and Analyzers,
while in the process of implementing the BCAL readout into geometry
of the monte carlo I noticed that the aluminum base plate on the inside
of the BCAL is 2.54 cm thick (==1inch) instead of 0.8cm.
So be aware that this is currently wrong in your geometry. I have not
yet finished the readout geometry but I will soon commit a change
to the BCAL geometry that will also include a 0.8cm thick inner base plate.

cheers,
Beni