Update core.

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

diff --git a/core b/core
index 5421ab0..47205c5 160000 (submodule)
--- a/core
+++ b/core
@@ -1 +1 @@
-Subproject commit 5421ab0971fa76a0ae98afbeffe899318c07780e
+Subproject commit 47205c58a02803a71bacb4c926207d81fbc18c13