Debian package updates.

* Split out a new libgtp-dev package.
* Updated dependencies.
diff --git a/debian/source/format b/debian/source/format
index af745b3..89ae9db 100644
--- a/debian/source/format
+++ b/debian/source/format
@@ -1 +1 @@
-3.0 (git)
+3.0 (native)