Cache known exchange types

Patch provided by GSerjo:
https://groups.google.com/forum/#!topic/rabbitmq-users/Gm7oFTaciKs
merge bug26507 into default
Switch to auto-properties, lots of cosmetic changes

Applied a patch by GSerjo.
merge bug26509 into default
Synchronise one more method in SessionManager

Patch by GSerjo.
merge bug26508 into default
Use a separate lock object in BlockingCell

Patch by GSerjo.
merge bug26510 into default
merge default into bug26505