Added apt.dat to groundnet / twr/ threshold / ils.xml files converter, made STG object elevation recalculator accept whole directory structures as input

utils/unit_convert.py

@@ -0,0 +1,12 @@
+#!/usr/bin/env python
+#-*- coding:utf-8 -*-
+
+import math
+
+def m2ft(m):
+	return m * 3.2808399
+
+def ft2m(ft):
+	return ft / 3.2808399
+
+