footprintinit.xml: The automatically calculated linc/sinc will now always be...

footprintinit.xml: The automatically calculated linc/sinc will now always be >= 1. References #686. 
ImagePolygon.h: 2012-05-14 Steven Lambright - Added safety to the calcImageBorderCoordinates method, along with the validSampleDim and validLineDim methods. This fixes seg faults. Fixes #686. 

git-svn-id: http://subversion.wr.usgs.gov/repos/prog/isis3/trunk@4383 41f8697f-d340-4b68-9986-7bafba869bb8