some work in the parser and refactoring

added a new math operator: assign
now we can assign a value to a variable (not finished yet)




git-svn-id: svn://ttmath.org/publicrep/ttmath/trunk@1137 e52654a7-88a9-db11-a3e9-0013d4bc506e

ttmath/ttmathtypes.h

@@ -395,7 +395,8 @@ namespace ttmath
 		err_unknown_object,
 		err_still_calculating,
 		err_in_short_form_used_function,
-		err_percent_from
+		err_percent_from,
+		err_assignment_requires_variable
 	};