added code to support data colocation and creation of modified files including colocated data; added support for a filter based on another variable data set (for example filtering winds on QI); quite a bit of refactoring to clean up code and handle longitude/latitude edge cases

git-svn-id: https://svn.ssec.wisc.edu/repos/glance/trunk@97 8a9318a1-56ba-4d59-b755-99d26321be01