SLING-4083 revert all changes from trunk, copied to branch https://svn.apache.org/repos/asf/sling/whiteboard/sseifert/SLING-4083_models_slingobject_threadlocal

git-svn-id: https://svn.apache.org/repos/asf/sling/trunk@1635446 13f79535-47bb-0310-9956-ffa450edef68