Last version of core (again).

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

diff --git a/core b/core
index 2023db9..6f84e15 160000 (submodule)
--- a/core
+++ b/core
@@ -1 +1 @@
-Subproject commit 2023db9b717479a0a79cbc0a833985b37ec14814
+Subproject commit 6f84e151da62e6c48392658e0246508bea9e950e