added ability to only generate images when the variable fails comparison (using the config file); created graphics.py and removed dependency on Keoni.maps.graphics; refactored plotting to reuse basemap and bounding axes where possible; added clear/close of figures

git-svn-id: https://svn.ssec.wisc.edu/repos/glance/trunk@59 8a9318a1-56ba-4d59-b755-99d26321be01