ISIS-933: fixing layout issues when the layout.xml HAS been specified... * was adding in properties to fieldsets twice, even if already in the fieldset. (This bug because previously I had been focusing on getting the auto-add for non-referenced properties to work, based on @MemberOrder)
Also: * ensuring that can reload dynamically without having to invalidate cache. This bug was due to the SpeificationCacheDefault ( which maintains two separate hashmaps to cache specs) getting out-of-whack internally ... specId holding one version of a spec, while className holding a different on. * remove versionSequence from SimpleObject (as now have the Persistable_... mixins).