various refactoring to handle data without lon/lat; new image making methods...

various refactoring to handle data without lon/lat; new image making methods for 2D data just shown as an image (not mapped) and for line plots; changed plotting module to use a pseudo-factory pattern for generating correct plot set; created new filter to make ipopp data into an image; created new filter to collapse multi-dimensional data

git-svn-id: https://svn.ssec.wisc.edu/repos/glance/trunk@92 8a9318a1-56ba-4d59-b755-99d26321be01