A couple of performance improvements

o Created and uses PrimitiveLongIterator for getPropertyKeys(). Should be
  used for more as well.
o Use individual statement operation parts to remove the tiny
  StatementOperations delegation at the top.
o TxState#hasChanges() is cheaper
o StateHandlingStatementOperations#getPropertyKeys and getProperty
  just delegates if there's no tx changes.
Merge pull request #934 from tinwelint/2.0-minor-perf-improvements

A couple of performance improvements. co-author @lassewesth, merging.
Follows new naming convention (KernelTransaction instead of TransactionContext)
Enable consistency checking of schema store.

So far only checking integrity of dynamic record chains.
Making MergeAst a parser concern
Merge pull request #944 from systay/2.0-merge-ast-in-the-parser

Making MergeAst a parser concern
Merge remote-tracking branch 'upstream/2.0' into master-merge-into-2.0

Conflicts:
	community/cypher/src/main/scala/org/neo4j/cypher/internal/executionplan/PartiallySolvedQuery.scala