Renaming and cleanup of code in QueryGraph
Make sure we do not inline expression when identifiers are used more then one time

o Introduce trait ScopeIntroducingExpression to mark expressions that introduce new identifiers
o Do not run the inliner on update clauses and on scope introducing expressions
o More testing
QueryGraph.equivalent must check skip and limit
Fix: disable ronja for queries containing with
Merge pull request #2347 from boggle/ronja-with

Fix-Ups for preparing WITH