Updates core version.

Signed-off-by: Vincent Zanotti <vincent.zanotti@polytechnique.org>

diff --git a/core b/core
index 2ce9862..c12e921 160000 (submodule)
--- a/core
+++ b/core
@@ -1 +1 @@
-Subproject commit 2ce986248cd0aad8fce405f188cf554da5610713
+Subproject commit c12e921105fecafcf2be1fce956d54dc7a148bfb