Change term 'gear' to gradientForest object or gf.name, depending on context.
Put checks into generic functions to avoid them being called on the wrong objects.

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/gradientforest@35 edb9625f-4e0d-4859-8d74-9fd3b1da38cb