* core: new reverse_proxy option prevents ikiwiki from trying to detect
how to make self-referential URLs by using the CGI environment variables,
for instance when it's deployed behind a HTTP reverse proxy
+ (Closes: #745759)
* core: the default User-Agent is now "ikiwiki/$version" to work around
ModSecurity rules assuming that only malware uses libwww-perl
* core: use protocol-relative URLs (e.g. //www.example.com/wiki) so that