bbbikeleaflet: removed Route layer control

The route should always be visible, and we need space for more layers
in the future.
storable target: make sure no other files are rebuilt

The "storable" Makefile target is called in strassen-storable.t. It
might happen that a temporal change in bbbike-temp-blockings caused
bbbike-temp-blockings-optimized to be rebuilt while running the
"storable" target.

Now "storable" has no dependencies (the up-to-date check is done by a
shell "if test"), so this cannot happen anymore.
data update (mainly Ahrensfelde preparations)