More read/write tests for town and outdoors, including maps/dialogue

Fixes:
- For towns, the "has tavern" flag was not saved or loaded
- Outdoor roads were not saved or loaded
- For outdoor encounters, the "can't flee" and "forced" flags were not loaded, and "forced" was not saved
--> These two flags have also been separated in the code

test/files/maps/fields_out.map

@@ -0,0 +1,5 @@
+1,2,3,4,5
+6,7,8,9,10
+11,12,13&9,14,15
+16,17,18&25,19,20
+21,22,23&25,24,25