Use last version of the core.

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

diff --git a/core b/core
index c210416..f76b8d9 160000 (submodule)
--- a/core
+++ b/core
@@ -1 +1 @@
-Subproject commit c21041687b7e324a1804a712fe2580593fb9cbe5
+Subproject commit f76b8d9256f204875d91100341e6a6249bda15ce