Renaming of mako files

I'm suggesting to use the pattern <file_name>.mako.<file_type> for Mako files in the repo. In this way we know the file is a Mako template and we know the actual type of the file. And with this pattern GitHub and our editors know how to color the content of the files. E.g. https://github.com/geoadmin/mf-geoadmin3/blob/master/app/index.mako versus https://github.com/geoadmin/mf-geoadmin3/blob/dev_makofilename/app/index.mako.html.

Note: I don't think app/src/print/partials/form.mako.html should be a Mako template, but this is a separate discussion.