Bump to 6.0.43, use go generate

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

fields/6.0.43/UserGroup.json

@@ -0,0 +1,5 @@
+{
+    "name": ".{1,128}",
+    "qos_rate_max_up": "-1|[2-9]|[1-9][0-9]{1,4}|100000",
+    "qos_rate_max_down": "-1|[2-9]|[1-9][0-9]{1,4}|100000"
+}