Common update:

-added VBo batch rendering (current default, no render mode switch yet)
-fixed camera positioning calculation
-fixed buffer issue with WebGL
-added viewport scalling (at least 300 pixels height). Pixels are scalled if screen is bigger.
-center demos gameplay area
-added fullpage html template for Emscripten build

demos/utils/source/ecs_utils/gfx/buffer.d

@@ -55,10 +55,10 @@ struct Buffer
         glBufferStorage(GL_ARRAY_BUFFER,size*count,data, flags);
     }*/
 
-    void bufferSubData(uint size, uint offset, void* data) nothrow
+    void bufferSubData(BindTarget target, uint size, uint offset, void* data) nothrow
     {
-        bind(BindTarget.array);
-        glBufferSubData(GL_ARRAY_BUFFER,offset,size,data);
+        bind(target);
+        glBufferSubData(target,offset,size,data);
     }
     
     void map(BindTarget target) nothrow