refactor of post-processing

- moves collapse into a dedicated set of functions / files
 - make collapse scenarios distinct (slight performance cost)
 - reduce verbosity for short name segments (now actually working, was supposed to do so before)

features/foot/area.feature

@@ -3,6 +3,7 @@ Feature: Foot - Squares and other areas
 
     Background:
         Given the profile "foot"
+        Given a grid size of 200 meters
 
     @square
     Scenario: Foot - Route along edge of a squares

features/foot/names.feature

@@ -3,6 +3,7 @@ Feature: Foot - Street names in instructions
 
     Background:
         Given the profile "foot"
+        Given a grid size of 200 meters
 
     Scenario: Foot - A named street
         Given the node map

features/foot/restrictions.feature

@@ -4,6 +4,7 @@ Feature: Foot - Turn restrictions
 
     Background:
         Given the profile "foot"
+        Given a grid size of 200 meters
 
     @no_turning
     Scenario: Foot - No left turn