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/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;