imported pmaker.utils.{chaincalls,normpath} from python-jinja2:jinja2_cui.utils
added test cases for pmaker.utils.{chaincalls,normpath}, and fixed some PEP8 errors/warns
added new internal API pmaker.tenjinwrapper.render to migrate to jinja2 smoothly
fixed a PEP8 error
made it can handle cases if  is not given
switched to new internal API to render templates