added to a map, using the resolutions/scales/etc. that were originally set, and also
keeping ahold of all the new options set on the layer since we created it, like
isBaseLayer, to correspond to behavior of Size.clone and the like.
git-svn-id: http://svn.openlayers.org/trunk/openlayers@1662 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf