Fix syntax for procedure declarations

Allow semi after the "returns" keyword.

opengeode/sdl92Lexer.py

-# $ANTLR 3.1.3 Mar 17, 2009 19:23:44 sdl92.g 2016-08-22 11:16:15
+# $ANTLR 3.1.3 Mar 17, 2009 19:23:44 sdl92.g 2016-09-16 14:37:44
 
 import sys
 from antlr3 import *

sdl92.g

@@ -298,7 +298,7 @@ procedure
 procedure_result
         :       ('->' | RETURNS)
                 variable_id?
-                sort
+                sort end?
         ->      ^(RETURNS variable_id? sort)
         ;