Update lib submodule

diff --git a/rpp-lib b/rpp-lib
index a51911e6286f0aa67562634cab9db68620e7cc89..e4e591de881211ff8325716e902540e77623d2fd 160000 (submodule)
--- a/rpp-lib
+++ b/rpp-lib
@@ -1 +1 @@
-Subproject commit a51911e6286f0aa67562634cab9db68620e7cc89
+Subproject commit e4e591de881211ff8325716e902540e77623d2fd