nhrpd: implement next hop resolution protocol

This provides DMVPN support and integrates to strongSwan. Please read
README.nhrpd and README.kernel for more details.
diff --git a/.gitignore b/.gitignore
index a281555..a8da62f 100644
--- a/.gitignore
+++ b/.gitignore
@@ -27,6 +27,7 @@
 quagga-[0-9.][0-9.][0-9.]*.tar.gz.asc
 .nfs*
 libtool
+.libs
 .arch-inventory
 .arch-ids
 {arch}
@@ -34,6 +35,7 @@
 .msg
 .rebase-*
 *~
+*.o
 *.loT
 m4/*.m4
 !m4/ax_sys_weak_alias.m4