mod_survey: Translation tweaks
mod_admin: Do foldr over the blocks instead of foldl

This allows higher-priority modules to override or disable blocks that
lower-priority modules have defined, instead of the other way around.
mod_admin: Speed up admin edit page JS performance

The save button script was veryinefficient script running on the
window scroll-event; this is now put inside a timeout function.
mod_development: Rescan templates when new one has been found
mod_admin: make pane visible for "Add category"

fixes #591
(cherry picked from commit 54dffcdb9c71084e84c8a239634bf4381ae3af47)