looking up package path at import time requires Py3.3+
fix base path finding for in-place compilation
properly support '**' pattern in file selection
extract normal cythonize script test from package compilation test as the latter is not supported in Py3.[012]

--HG--
rename : tests/build/cythonize_script.srctree => tests/build/cythonize_script_package.srctree