As usual, this is mostly for configuration templates that you use for
multiple servers, that sort of things, eg.
@if !environment("ADMIN")
@error "Environment variable ADMIN is not set"
@endif
This also adds a change in conf.c so @define, @error and
@warning are skipped in @if blocks that evaluate to false
(that's obviously what everyone wants :D). So that fixes a
previous bug with @define in @if.
Bram Matthys
3dd449139b