Rename ol.extent.transform to ol.extent.applyTransform

This gives more consistency with ol.proj.applyTransform, allowing us to add a more convenient ol.extent.transform method that takes projection-like arguments.

src/ol/source/bingmapssource.js

@@ -139,7 +139,8 @@ ol.source.BingMaps.prototype.handleImageryMetadataResponse =
                 var maxZ = coverageArea.zoomMax;
                 var bbox = coverageArea.bbox;
                 var epsg4326Extent = [bbox[1], bbox[0], bbox[3], bbox[2]];
-                var extent = ol.extent.transform(epsg4326Extent, transform);
+                var extent = ol.extent.applyTransform(
+                    epsg4326Extent, transform);
                 var tileRange, z, zKey;
                 for (z = minZ; z <= maxZ; ++z) {
                   zKey = z.toString();