[request] enhanced user[_rql]_callback method, allowing to call other js variant, eg one of userCallback, userCallbackThenUpdateUI, userCallbackThenReloadPage (the default). Also benefit from the new magic js object.

option_group_changed('port', 'main', 'web')
option_group_changed('query-log-file', 'main', 'web')
option_group_changed('profile', 'main', 'web')
option_group_changed('max-post-length', 'main', 'web')