Added "base path override" config option that makes all links and
redirects work with your reverse proxy.
Fixed post config update reload to work properly.
Make redirects and ajax calls use relative pathing.
I changed the download urls, because the current way with segments
(having the parameters between slashes) was causing problems with long
encoded urls, since a segment can be no longer than 255 characters. It
was changed to use regular url parameters which have no such limit on
length.
