Bugfixes and some tests

[maglar0]

• 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.