Master transaction manager use TTID as index.

- AnswerInformationLocked give ttid instead of tid
- Master transaction manager always use ttid in data structures
- It's no more makes sense to check if the tid is greater than the last
generated as it never comes back from a storage, just check if the ttid is
well known by the transaction manager.
- Rename all tid variable that now hold a ttid
- Transaction manager's queue contains ttids but the corresponding tids are
increasing to keep commit order.
- Adjust tests

git-svn-id: https://svn.erp5.org/repos/neo/trunk@2613 71dcc9de-d417-0410-9af5-da40c76e7ee4