atomic handling of open/committing tx bitsets and array
TxRollbackListener

Merge branches 'master' and 'txcommit-atomic' of https://github.com/h2database/h2database into txcommit-atomic

Support DISTINCT in Java aggregates

Atomic change of transaction state

 Split off Transaction TransactionMap VersionedValue 

TransactionStore move into separate org.h2.mvstore.tx package

Encapsulate TransactionStore.store field in preparation to a move

encapsulate TransactionStore.store field in preparation to a move into a separate package  and susequent split

Make MVMap to operate in non-blocking fashion

generate less garbage for String substring+trim

# Conflicts:
#	h2/src/main/org/h2/mvstore/MVStore.java

Minor free space accointing changes

Remove unexpected check for column count in MergeUsing

# Conflicts:
#	h2/src/main/org/h2/mvstore/FreeSpaceBitSet.java
#	h2/src/main/org/h2/mvstore/MVStore.java

filestore.clear() added, verifyLastChunk() moved to make assertions happy