tests/bridgefall: New; exercising splashing of bridges

Stuff sitting on bridges isn't covered, yet.  tests/fire has some.  To
be moved here eventually.

The test exposes bugs.  They're marked "BUG:" in the test input.

Signed-off-by: Markus Armbruster <armbru@pond.sub.org>

tests/bridgefall/setup-POGO

@@ -0,0 +1,47 @@
+|| sectors
+desi 0,0 c
+desi 2,0 f
+desi 1,-1:1 #
+edit l 3,-1 e 100 s = S =
+edit l -1:0,-2:-1 e 20 s = S =
+edit l 1,-3 e 20 s @ S @
+edit l 2:3,-4:-2 e 100 s = S =
+des 3,-5 +
+des 8,2 -
+edit l -2:3,1:2 ?des=. e 100 s = S =
+edit l 1,3 e 100 s = S =
+desi 3,3 #
+desi -1,3 #
+edit l 6,0 e 100 s @ S @
+edit l 8,0 e 100 s = S =
+edit l -3,1 e 20 s @ S @
+| mark sectors of interest
+terr * ?des== 1
+terr * ?des=# 1
+terr * ?des=@ 1
+| populate
+give c * ?des#. 100
+edit l 0:2,0 e 100
+edit l * ?des=# e 20
+|| country#1
+add 1 1 1 p
+edit c 1 s 4 b 640 M 25000 T 100
+give m 2,0 5
+give g 2,0 7
+give s 2,0 100
+edit l * ?des#.&des#=&des#@&des#- o 1 O 1
+edit l 0,-2 o 1 O 1
+edit l 3,1 o 1 O 1
+|| country#2
+add 2 2 2 p
+| make country active, so it gets bulletins
+edit c 2 s 4 b 640 M 25000 T 100
+edit l * ?des#.&own=0 o 2 O 2
+edit l -1,3 o 2 O 2
+|| relations
+decl h 1 2
+decl h 2 1
+|| show initial state here to help maintainers
+cens * ?des#.
+comm * ?des#.
+map *