clear figures after use; correctly check if a file has a missing value before...

clear figures after use; correctly check if a file has a missing value before attempting to get it; also pull the correct missing value for file b if it has a different variable name than file a

git-svn-id: https://svn.ssec.wisc.edu/repos/glance/trunk@54 8a9318a1-56ba-4d59-b755-99d26321be01