[apps/sequence] Change default XNT text to 'n'

Change-Id: I917c09dd1c4f63a5988962b4c4f18f57e073a2af

apps/sequence/app.cpp

@@ -33,4 +33,8 @@ Context * App::localContext() {
   return &m_nContext;
 }
 
+const char * App::XNT() {
+  return "n";
+}
+
 }

apps/sequence/app.h

@@ -15,6 +15,7 @@ public:
   App(Container * container, Poincare::Context * context);
   InputViewController * inputViewController();
   Poincare::Context * localContext() override;
+  const char * XNT() override;
 private:
   SequenceStore m_sequenceStore;
   Poincare::VariableContext m_nContext;