use completely separate workspaces for tests to fix cleanup on failures (and to make sharding/parallel test runs straight forward)

fix name setup for package __init__ modules, make sure package is registered when importing its __init__ module; fixes initial_file_path test in Py3.3

clean up code generation in CmpNode and fix bug #784: conflicting result types for cascaded comparisons

--HG--
rename : docs/src/tutorial/pypy.rst => docs/src/userguide/pypy.rst