Bump to 6.0.43, use go generate

Also moved fetching of JSON information to Go for cross-OS usage.

fields/6.0.43/Wall.json

@@ -0,0 +1,9 @@
+{
+    "map_id": "",
+    "a": ["^([-]?[\\d]+[.]?[\\d]*)$"],
+    "b": ["^([-]?[\\d]+[.]?[\\d]*)$"],
+    "id": "",
+    "heightInMeters": "^([-]?[\\d]+[.]?[\\d]*)$",
+    "thicknessInMeters": "^([-]?[\\d]+[.]?[\\d]*)$",
+    "type": ""
+}