change_hook_active_link: pass update_cache_document_options @ses.
Now when changing the global settings, it will not simply copy the new values for the global settings to the document-options cache, but also check session-specific settings. This doesn't really matter yet, since the options in question can't be set on a per-session basis, but is in preparation for future changes.
This allows code to use document->cached instead of
find_in_cache(document->uri), thereby increasing the likelihood
of getting the correct cache entry.
This should fix Bug 756 - "assertion (cached)->object.refcount >= 0 failed"
after HTTP proxy was changed.
Patches for this were written by me and then later by Jonas.
This commit combines our independent implementations.
