An un-initialized field in the configless code path leads to a crash on the first request.

Error and warning messages are prefixed with "error: " and "warning: " correspondingly to ease integration with automated tooling. `yywarn' function added. Off-by-one line numbers in warnings are fixed. Two error messages are reworded to avoid repeating like "error: error in server directive" or "error: syntax error".

copy it to `/etc/rc.d`, write your config in `/etc/gmid.conf` and launch using `rcctl enable gmid && rcctl start gmid`.