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/webgl/webglimagelayerrenderer.js

@@ -160,7 +160,8 @@ ol.renderer.webgl.ImageLayer.prototype.renderFrame =
   var hints = frameState.viewHints;
 
   if (!hints[ol.ViewHint.ANIMATING] && !hints[ol.ViewHint.INTERACTING]) {
-    var image_ = imageSource.getImage(frameState.extent, viewResolution);
+    var image_ = imageSource.getImage(
+        frameState.extent, viewResolution, view2DState.projection);
     if (!goog.isNull(image_)) {
       var imageState = image_.getState();
       if (imageState == ol.ImageState.IDLE) {

src/ol/renderer/webgl/webgltilelayerrenderer.js

@@ -281,12 +281,16 @@ ol.renderer.webgl.TileLayer.prototype.renderFrame =
   var gl = mapRenderer.getGL();
 
   var view2DState = frameState.view2DState;
+  var projection = view2DState.projection;
   var center = view2DState.center;
 
   var tileLayer = this.getTileLayer();
   var tileSource = tileLayer.getTileSource();
   var tileSourceKey = goog.getUid(tileSource).toString();
   var tileGrid = tileSource.getTileGrid();
+  if (goog.isNull(tileGrid)) {
+    tileGrid = ol.tilegrid.getForProjection(projection);
+  }
   var z = tileGrid.getZForResolution(view2DState.resolution);
   var tileResolution = tileGrid.getResolution(z);
   var tileRange = tileGrid.getTileRangeForExtentAndResolution(
@@ -365,12 +369,12 @@ ol.renderer.webgl.TileLayer.prototype.renderFrame =
     var tilesToDrawByZ = {};
     tilesToDrawByZ[z] = {};
 
-    var isLoaded = function(tile) {
+    var getTileIfLoaded = this.createGetTileIfLoadedFunction(function(tile) {
       return !goog.isNull(tile) && tile.getState() == ol.TileState.LOADED &&
           mapRenderer.isTileTextureLoaded(tile);
-    };
+    }, tileSource, tileGrid, projection);
     var findLoadedTiles = goog.bind(tileSource.findLoadedTiles, tileSource,
-        tilesToDrawByZ, isLoaded);
+        tilesToDrawByZ, getTileIfLoaded);
 
     var tilesToLoad = new goog.structs.PriorityQueue();
 
@@ -380,7 +384,7 @@ ol.renderer.webgl.TileLayer.prototype.renderFrame =
       for (y = tileRange.minY; y <= tileRange.maxY; ++y) {
 
         tileCoord = new ol.TileCoord(z, x, y);
-        tile = tileSource.getTile(tileCoord);
+        tile = tileSource.getTile(tileCoord, tileGrid, projection);
         if (goog.isNull(tile)) {
           continue;
         }
@@ -459,7 +463,7 @@ ol.renderer.webgl.TileLayer.prototype.renderFrame =
   }
 
   this.updateUsedTiles(frameState.usedTiles, tileSource, z, tileRange);
-  tileSource.useLowResolutionTiles(z, frameState.extent);
+  tileSource.useLowResolutionTiles(z, frameState.extent, tileGrid);
   this.scheduleExpireCache(frameState, tileSource);
 
   goog.vec.Mat4.makeIdentity(this.texCoordMatrix_);