SotBE S6: make it impossible to block gelleon landing sites

Previously, if you had a unit on the transport galleon landing site,
the galleon would not be able to unload its troops.  Now, the unloading
condition kicks in when the ship gets to the landing site or if ends up
next to an enemy unit.

data/campaigns/Son_Of_The_Black_Eye/scenarios/06_Black_Flag.cfg

@@ -322,13 +322,28 @@
 
         [filter]
             type=Transport Galleon
+            [not]
+                [filter_wml]
+                    [variables]
+                        landed=yes
+                    [/variables]
+                [/filter_wml]
+            [/not]
 
-            [filter_wml]
-                [variables]
-                    destination_x=$x1
-                    destination_y=$y1
-                [/variables]
-            [/filter_wml]
+            [and]
+                [filter_wml]
+                    [variables]
+                        destination_x=$x1
+                        destination_y=$y1
+                    [/variables]
+                [/filter_wml]
+
+                [or]
+                    [filter_adjacent]
+                        side=1,5
+                    [/filter_adjacent]
+                [/or]
+            [/and]
         [/filter]
 
         [modify_unit]
@@ -337,6 +352,9 @@
             [/filter]
 
             goto_x,goto_y=1,30
+            [variables]
+                landed=yes
+            [/variables]
         [/modify_unit]
 
         {RANDOM 0..2}