Added aggr layer module to replace pooling for better naming.

Author: PatReis

changelog.md

@@ -12,6 +12,7 @@ v3.0.2
   The behaviour of `GatherNodes` has changed a little in that it first splits and then concatenates. The default parameters now have `split_axis` and `concat_axis` set to 2. `concat_indices` has been removed.
   The default behaviour of the layer however stays the same.
 * An error in layer `FracToRealCoordinates` has been fixed and improved speed.
+* Added 
 
 
 v3.0.1