Remove '--' argument

Since functions cannot start with '-' (and funky names are discouraged
anyway), it only adds more complexity to the arg router.

bin/fff

 
 
 usage() {
-    usage_is "[-I|--include module] [--] function [args...]"
+    usage_is "[-I|--include module] function [args...]"
 }
 
 includes=""
         "")
             usage
             ;;
-        --)
-            shift 1
-            break
-            ;;
         *)
             break;
             ;;