Some debugging with function formals.

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/spatial-tools@136 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
More debugging on focal_hpc and rasterEngine.  New function: predict.rasterEngine (name will probably change).  Documentation updates.

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/spatial-tools@137 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
Switched to overriding predict (for now).

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/spatial-tools@138 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
git-svn-id: svn://svn.r-forge.r-project.org/svnroot/spatial-tools@139 edb9625f-4e0d-4859-8d74-9fd3b1da38cb