Set flags of dynamic loader so that symbols are global.

    * src/dynamic_graph/__init__.py.

src/dynamic_graph/__init__.py

@@ -3,7 +3,15 @@ Copyright (c) 2010 CNRS
 Author: Florent Lamiraux
 """
 
+import sys, dl
+flags = sys.getdlopenflags()
+# Import C++ symbols in a global scope
+# This is necessary for signal compiled in different modules to be compatible
+sys.setdlopenflags(dl.RTLD_NOW|dl.RTLD_GLOBAL)
 from wrap import *
+# Recover previous flags
+sys.setdlopenflags(flags)
+
 import entity, signal_base
 import re