Implements the "transactional retire and settle immediately" option for
transactions as specified in AMQP 1.0 in the qpid::messaging C++ client.

NOTE: Transactions over AMQP 1.0 require proton 0.9 or greater.  With older
versions, attempting a transactions over AMQP 1.0 will raise a link-detached
exception "Node not found: tx-transaction"

1. Added descriptor list to Variant with support in Encoder and PnData.

Required to support transactions, need to be able to create described lists.
Variant changes are source and binary compatible.

A Variant now has a Variant::List of descripors which can be numeric or string.
Nested descriptors are implemented by putting multiple descriptors in the list.

Other minor changes:
- Variant refactor: don't delete impl on every assignment.
- Add Variant constructors that take a string encoding.
  (new constructors, not defaulted arguments, so the change is binary and source compatible.)
- Growable buffer support for Encoder.
- Printing described Variant prints descriptors in form @descriptor value

2. Added transaction support to AMQP 1.0 client code

Added messaging/amqp/Transaction.h,cpp: transaction logic
- communicate with coordinator, send declare/dischange messages.
- add tx state info to transfers and acknowledgements.
- Sync session after discharge.
- A transactional session automatically acks any message retrieved by fetch/get
  to bring them into the transaction. This is consistent the 0-10 client.

Minor fixes to existing client code:
- Fix use of pn_drain API in C++ client to work with C++ and Java brokers.
- Make amqp::Exception derive from qpid::Exception

3. Fixes to existing broker code:

- Incoming.cpp fix: start async completion before processing message.
- Delay accept of dischage message till commit is complete.
- newSession - handle failover during session creation.

4. Added tests

interop_tests.py: transaction tests that can run against an external broker, see comments.

ha_tests.py: Enable transaction tests over AMQP 1.0.

Minor test fixes:
- brokertest.py don't set default logging if QPID_LOG env vars set.
- brokertest.py Pass kwargs to broker() create function.
- qpid-receive: capacity should never be larger than message count.
- Accept user:pass as well as user/pass in Url.
- brokertest.py: Always do a ready() check on all brokers.

If proton < 0.9 is used, transaction tests will be skipped or will downgrade to
the amqp0-10 protocol with a printed warning.

git-svn-id: https://svn.apache.org/repos/asf/qpid/trunk@1662743 13f79535-47bb-0310-9956-ffa450edef68

git-svn-id: https://svn.apache.org/repos/asf/qpid/trunk@1609098 13f79535-47bb-0310-9956-ffa450edef68

- Separate Wall clock time uses from other time
  * (assumed that any time with respect to the epoch is wallclock)
- For Posix use CLOCK_MONOTONIC for all non wall clock purposes
  so that changing system time doesn't affect internal timekeeping
- For Windows kept the same time keeping scheme.

git-svn-id: https://svn.apache.org/repos/asf/qpid/trunk@1607140 13f79535-47bb-0310-9956-ffa450edef68

- shared_ptr no longer has a default conversion to bool.
- Change in default destructor semantics: by default destructors are now
  not allowed to throw exceptions.
- stringstream no longer has a default conversion to string.

git-svn-id: https://svn.apache.org/repos/asf/qpid/trunk@1584199 13f79535-47bb-0310-9956-ffa450edef68

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