When a delayed store is processed, don't take the lock if the transaction
is no more registered (may have been aborted due to a timeout with the
delayed store).
Change the TransactionManager API: add register() that must be called before
any storeObject/storeTransaction operation.

git-svn-id: https://svn.erp5.org/repos/neo/trunk@2159 71dcc9de-d417-0410-9af5-da40c76e7ee4