Reduces the indirection in fcgi.c, starts to make the struct template opaque, simplifies the template usage. All with a net negative :-) reads fine to stsp@ (thanks!)

This greatly reduces the number of tp_puts() calls: gotwebd' pages.tmpl goes from 444 to 190. Otherwise, this doesn't produce other observable changes.

unused, and was dropped by other copies of proc.c; reduces the diff with httpd' proc.c.

not particularly interesting (and to be fair also quite large) but it doesn't touch untrusted data: all it does is waiting for signals to either reload the config (and the socket) or terminate.

otherwise we end up using stack garbage when the gemini server doesn't send a `lang' attribute. Problem reported by Javier Bravo, thanks!

add a regress for this case.