In Orthographic, XYRange() and SetCoordinate() were modified because XYRange()...

In Orthographic, XYRange() and SetCoordinate() were modified because XYRange() was returning the wrong x/y ranges caused by a false failure in SetCoordinate(). Added a case to the unit test to check the x/y values when the lat/lon ranges are smaller than the possible range of the projection (half the planet). Fixes #798.

git-svn-id: http://subversion.wr.usgs.gov/repos/prog/isis3/trunk@5051 41f8697f-d340-4b68-9986-7bafba869bb8