Formats now support reprojection using internalProjection and

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

lib/OpenLayers/Format.js

@@ -11,6 +11,34 @@
  */
 OpenLayers.Format = OpenLayers.Class({
     
+    /**
+     * APIProperty: externalProjection
+     * {<OpenLayers.Projection>} When passed a externalProjection and
+     *     internalProjection, the format will reproject the geometries it
+     *     reads or writes. The externalProjection is the projection used by
+     *     the content which is passed into read or which comes out of write.
+     *     In order to reproject, a projection transformation function for the
+     *     specified projections must be available. This support may be 
+     *     provided via proj4js or via a custom transformation function. See
+     *     {<OpenLayers.Projection.addTransform>} for more information on
+     *     custom transformations.
+     */
+    externalProjection: null,
+
+    /**
+     * APIProperty: internalProjection
+     * {<OpenLayers.Projection>} When passed a externalProjection and
+     *     internalProjection, the format will reproject the geometries it
+     *     reads or writes. The internalProjection is the projection used by
+     *     the geometries which are returned by read or which are passed into
+     *     write.  In order to reproject, a projection transformation function
+     *     for the specified projections must be available. This support may be
+     *     provided via proj4js or via a custom transformation function. See
+     *     {<OpenLayers.Projection.addTransform>} for more information on
+     *     custom transformations.
+     */
+    internalProjection: null,
+
     /**
      * Constructor: OpenLayers.Format
      * Instances of this class are not useful.  See one of the subclasses.