Fixes#5808
Seems some gcc:s will generate the code as sign extending. Mine does not,
but this should be more correct anyhow.
Added small stringify test to serialization_test for inet_address
1. Move tests to test (using singular seems to be a convention
in the rest of the code base)
2. Move boost tests to test/boost, other
(non-boost) unit tests to test/unit, tests which are
expected to be run manually to test/manual.
Update configure.py and test.py with new paths to tests.