Bugfixes and some tests

- The bugfixes I sent you a mail about (with the small change that I use another error code).
- The test of client/server packet delivery I sent you mail about (with slightly cleaned up code)
- Changed the get time function in Chicago to use a callback in order to make the unit test reproducible and more sane (i.e. not running it in real time).
- Unit test for reliable transport using messager
- Bugfix from kostko's fork to messager. Without this the new unit test fails for some choices of stream sizes and delivery latencies etc.