Preliminary work to allow for other dataTypes to be output.  New function: dataType_converter.  Modded binary_image_write and create_blank_raster.

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/spatial-tools@123 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
git-svn-id: svn://svn.r-forge.r-project.org/svnroot/spatial-tools@124 edb9625f-4e0d-4859-8d74-9fd3b1da38cb