Use last version of the core.

Signed-off-by: Florent Bruneau <florent.bruneau@polytechnique.org>

diff --git a/core b/core
index e4f6c7d..80d0423 160000 (submodule)
--- a/core
+++ b/core
@@ -1 +1 @@
-Subproject commit e4f6c7d0410bdc8c0f62abc4ee17092dbc52126c
+Subproject commit 80d0423e13a1fbf932fa8b27f323af0d504a7873