Add NSH addroute and delroute commands

drivers/Kconfig

@@ -440,5 +440,3 @@ endif
 comment "System Logging Device Options"
 
 source drivers/syslog/Kconfig
-
-

net/Kconfig

@@ -68,8 +68,7 @@ config NET_SOCKOPTS
 
 config NET_BUFSIZE
 	int "Network packet size"
-	default 562 if !NET_TCP && NET_UDP && !NET_SLIP
-	default 420 if NET_TCP && !NET_UDP && !NET_SLIP
+	default 562 if !NET_SLIP
 	default 296 if NET_SLIP
 	---help---
 		uIP buffer size.  Default: 562

net/net_allocroute.c

@@ -41,6 +41,7 @@
 
 #include <stdint.h>
 #include <errno.h>
+#include <assert.h>
 
 #include <arch/irq.h>