this has been hardcoded to false for quite some time now

clean up some javadoc and some throws clauses

Create UndoLog only when necessary and remove outdated code

Remove some PageStore+MVCC leftovers

Fix inconsistencies in checks for transaction isolation level

Fix issues with testing on latest Java versions

# Conflicts:
#	h2/src/main/org/h2/mvstore/tx/TxDecisionMaker.java

Leftovers handling

Fix for issue #1220

merge

Postpone session.endStatement() until after commit.

Test utilities only once during TestAll and fix OOME in TestOptimizations