Simplify template parameter specialization and default

Author: Bolpat

spec/template.dd

@@ -288,10 +288,7 @@ $(H3 $(LNAME2 template_type_parameters, Type Parameters))
 
 $(GRAMMAR
 $(GNAME TemplateTypeParameter):
-    $(GLINK_LEX Identifier)
-    $(GLINK_LEX Identifier) $(GLINK TemplateTypeParameterSpecialization)
-    $(GLINK_LEX Identifier) $(GLINK TemplateTypeParameterDefault)
-    $(GLINK_LEX Identifier) $(GLINK TemplateTypeParameterSpecialization) $(GLINK TemplateTypeParameterDefault)
+    $(GLINK_LEX Identifier) $(GLINK TemplateTypeParameterSpecialization)$(OPT) $(GLINK TemplateTypeParameterDefault)$(OPT)
 
 $(GNAME TemplateTypeParameterSpecialization):
     $(D :) $(GLINK2 type, Type)
@@ -511,10 +508,7 @@ $(H3 $(LNAME2 template_value_parameter, Value Parameters))
 
 $(GRAMMAR
 $(GNAME TemplateValueParameter):
-    $(GLINK2 type, BasicType) $(GLINK2 declaration, Declarator)
-    $(GLINK2 type, BasicType) $(GLINK2 declaration, Declarator) $(GLINK TemplateValueParameterSpecialization)
-    $(GLINK2 type, BasicType) $(GLINK2 declaration, Declarator) $(GLINK TemplateValueParameterDefault)
-    $(GLINK2 type, BasicType) $(GLINK2 declaration, Declarator) $(GLINK TemplateValueParameterSpecialization) $(GLINK TemplateValueParameterDefault)
+    $(GLINK2 type, BasicType) $(GLINK2 declaration, Declarator) $(GLINK TemplateValueParameterSpecialization)$(OPT) $(GLINK TemplateValueParameterDefault)$(OPT)
 
 $(GNAME TemplateValueParameterSpecialization):
     $(D :) $(GLINK2 expression, ConditionalExpression)