Draft: Attempt at adding macros

I thought it might be useful to have some jinja macros to e.g. list our contacts or format links to egroups. I'm not having much luck following the docs though: I keep getting errors like

jinja2.exceptions.UndefinedError: 'macros_info' is undefined

even though macros_info is supposed to be the first thing you run to make sure it's working.