[Halld-offline] HDGeant EM issue resolved

[David Lawrence]

Hi Folks,

     Just an update that the problem I reported earlier with hdgeant 
crashing when EM background was enabled turned out to be a red herring. 
It was due to a stale version of hdds that I was linking against.

     Thanks to Richard for providing a working executable and set of all 
packages that allowed me to systematically link against them until the 
offending package was found.

-David