added max_length_chars to notification params

indra/llui/llnotifications.cpp

@@ -81,6 +81,7 @@ LLNotificationForm::FormButton::FormButton()
 
 LLNotificationForm::FormInput::FormInput()
 :	type("type"),
+	max_length_chars("max_length_chars"),
 	width("width", 0)
 {}
 

indra/llui/llnotifications.h

@@ -194,6 +194,7 @@ public:
 	{
 		Mandatory<std::string>	type;
 		Optional<S32>			width;
+		Optional<S32>			max_length_chars;
 
 		FormInput();
 	};