Make Bylevel and Level Overrides recognise Hatches and Patterns. If a H/P is placed on a particlar level, then it will use a H/P pre-defined for that level. This should also pave the way for H/P's to be overriden by level.
Make Bylevel / Level Overrides recognise Fills as well as H/P's. So that a H/P can be be overriden by a Fill and vice versa.