externalProjection properties. These allow for the reprojection of data --
OpenLayers users with SphericalMercator get this built in for EPSG:900913, and
other users can use the external proj4js library available from MapBuilder SVN
to add support for any number of projections. This means that featres can be,
for example, transformed from a KML doc in 4326 to Spherical Mercator before
being added to a layer, making using SphericalMercator slightly more enticing.
r=elemoine
(Closes#1039)
git-svn-id: http://svn.openlayers.org/trunk/openlayers@5516 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf
