filter out non-string args

pmanager/pmanager.py

@@ -142,6 +142,7 @@ class PManager:
         log("Launching! key: %s, opts: %s" % (key, options))
         tolaunch = self.ptable[key]
         if options is not None:
+            options = [ o for o in options if type(o) is str ]
             tolaunch = tolaunch + options
     
         log(tolaunch)