Support tile sources without configured projection

This change adds a lot of flexibility to working with tile
layers: Sources where the server projection or tile grid do not
matter can now be constructed without specifying a projection or
tile grid.

The tileUrlFunction/imageUrlFunction now also creates updated
URLs when the params of the layer change, so things like
mergeNewParams in ol2 will be possible.

A nice side effect of this whole change is that there is no more
duplicated code between tiled and single image WMS layers.

While I was at it, I also fixed a WMS 1.1.1 axis order issue
and incorrect STYLES params (STYLES=& instead of STYLES&).

src/ol/renderer/canvas/canvasimagelayerrenderer.js

@@ -79,7 +79,8 @@ ol.renderer.canvas.ImageLayer.prototype.renderFrame =
   var hints = frameState.viewHints;
 
   if (!hints[ol.ViewHint.ANIMATING] && !hints[ol.ViewHint.INTERACTING]) {
-    image = imageSource.getImage(frameState.extent, viewResolution);
+    image = imageSource.getImage(
+        frameState.extent, viewResolution, view2DState.projection);
     if (!goog.isNull(image)) {
       var imageState = image.getState();
       if (imageState == ol.ImageState.IDLE) {