Rename projection functions for a friendlier API

The following functions are renamed:

getTransform -> getTransformForProjections
getTransformFromCodes -> getTransform
transform -> transformWithProjections
transformWithCodes -> transform

With this change, the faster functions that avoid projection look-up
have longer names and are used internally, whereas the slower but
friendlier short name functions are available for users.

src/ol/source/bingmapssource.js

@@ -111,7 +111,7 @@ ol.source.BingMaps.prototype.handleImageryMetadataResponse =
                 };
               })));
 
-  var transform = ol.projection.getTransform(
+  var transform = ol.projection.getTransformFromProjections(
       ol.projection.get('EPSG:4326'), this.getProjection());
   var attributions = goog.array.map(
       resource.imageryProviders,

src/ol/source/source.js

@@ -38,7 +38,7 @@ ol.source.Source = function(sourceOptions) {
    */
   this.extent_ = goog.isDef(sourceOptions.extent) ?
       sourceOptions.extent : goog.isDef(sourceOptions.projection) ?
-          sourceOptions.projection.getExtent() : null;
+          this.projection_.getExtent() : null;
 
   /**
    * @private

src/ol/source/tiledwms.exports

@@ -1 +1 @@
-@exportSymbol ol.source.TiledWMS
+@exportSymbol ol.source.TiledWMS

src/ol/source/tilejsonsource.js

@@ -87,8 +87,8 @@ ol.source.TileJSON.prototype.handleTileJSONResponse = function() {
     var bounds = tileJSON.bounds;
     epsg4326Extent = new ol.Extent(
         bounds[0], bounds[1], bounds[2], bounds[3]);
-    extent = epsg4326Extent.transform(
-        ol.projection.getTransform(epsg4326Projection, this.getProjection()));
+    extent = epsg4326Extent.transform(ol.projection.getTransformFromProjections(
+        epsg4326Projection, this.getProjection()));
     this.setExtent(extent);
   } else {
     epsg4326Extent = null;