updated picoTCP to 1.4.0, lowered build optimization levels to -O2, improved selftest

ext/picotcp/test/python/ping_nat.py

@@ -0,0 +1,17 @@
+#!/usr/bin/python
+from  topology import *
+
+T = Topology()
+net1 = Network(T, 'nat0')
+net2 = Network(T)
+
+
+h1 = Host(T, net1, args="ping:172.16.2.1:")
+h2 = Host(T, net2)
+router1 = Host(T, net1, net2, args="natbox:172.16.2.2:")
+
+sleep(1)
+start(T)
+
+wait(h1)
+cleanup()