1) I modified build_visit to add zlib to the list of dependent libraries
   for silo in the config site file.

2) I added the option "--download-only", which only downloads the files.

3) I replaced davinci with euclid in the open build and install scripts.



git-svn-id: http://visit.ilight.com/svn/visit/trunk/src@11634 18c085ea-50e0-402c-830e-de6fd14e8384