added ability to write figs to file without displaying
added ability to write figs to file without displaying

git-svn-id: http://svn.code.sf.net/p/petavision/code/sandbox@6076 7c0444ca-5550-0410-9008-faecdbe78eb5

Former-commit-id: 189533127d03df8aba876d09a29cc03a69a4ba8f
PetaVision/OpenPV,dpaiton/OpenPV,dpaiton/OpenPV,PetaVision/OpenPV,dpaiton/OpenPV,PetaVision/OpenPV,PetaVision/OpenPV,dpaiton/OpenPV,dpaiton/OpenPV,dpaiton/OpenPV,PetaVision/OpenPV,dpaiton/OpenPV,dpaiton/OpenPV