[zope4py3] erp5: Switch python to gpython + spawn runwsgi via it; pre-activate bstr+ustr
As asked in pygolang!21 (comment 205820) hereby patches show how to adjust stack/erp5/ a bit to run programs via gpython instead of python. All patches except the last one should be good to merge, and mostly to master, because bstr+ustr activation happens only as the last step and all preceeding changes should be making preparatory steps only.
Please see individual patches for details.
Kirill