data update (minor)
radroute.html: fixed error in certain user click paths

The following click path caused an error: on the radroute.html page,
click on "routelist" button first, then use browser's back button,
then click on the "map" button of the same cycle route. This caused a
strange download dialog for a "image/" file (yes, without a real
subtype), and warnings about the use of "images/flag2_bl." and
"images/flag_ziel." (that is, without suffixes) in the errorlog.

Problem was: a click on routelist manipulated the form by basically
setting the "imagetype" form parameter to the empty string, and this
was never corrected back.
data update (mainly Stralau and Gross/Kleinziethen)
bbd.pod: added directive "linked"
.check_ortsschilder2: check using new directive "linked"
data update (ortsschilder: make use of new directive "linked")
data update (ortsschilder: more "linked" directives)
.check_ortsschilder_dist: now also is using "linked" directive
data update (minor survey)
data update (temp blockings with permanent=>1 entries)
data update
data update
PLZ.pm: added type "barracks" (Kaserne)

Needed for "Hottengrund (Kaserne)"
missing_streets helper: use get_street_type()

By using PLZ::get_street_type it's now possible to distinguish streets
and non-streets, so the huge exception list could be commented out.
missing_streets.pl: added a few exceptions

The old outcommented list is now deleted. With the exceptions, and the
forthcoming data updates, no more missing streets are found.
missing_streets exits with 1 if unhandled missing streets are found
new check: .check_missing_streets
removed remaining XXX_outdoor usages in scripts
DistDB: workaround for inaccessible points

BBBikeRouting's fix_position cannot handle inaccessible points. So if
either start or goal are not accessible, the route search fails.
Current workaround is to use the as-the-bird-flies distance instead.
fragezeichen2org: integration of nextcheck-less records and more

* new option --with-nextcheckless-records (by default enabled), to
  show also fragezeichen-like records without a nextcheck date
* new option --debug
* PLANNED is now PLAN (same length as TODO) and listed in org's
  SEQ_TODO
* item bodies show now all fragezeichen-like directives (XXX,
  add_fragezeichen etc)
* wording of section titles adapted
* Pod update