SpicePosition.h: 2010-12-07 Steven Lambright - Moved the cubic hermite splines...

SpicePosition.h: 2010-12-07 Steven Lambright - Moved the cubic hermite splines to member scope for efficiency. It was a significant overhead to keep reconstructing these. Created ClearCache() to help increase code reusability. 

git-svn-id: http://subversion.wr.usgs.gov/repos/prog/isis3/trunk@1303 41f8697f-d340-4b68-9986-7bafba869bb8