Add support for nxxm.

[nxxm](https://nxxm.github.io)

include/ftxui/component/event.hpp

@@ -0,0 +1,41 @@
+#ifndef FTXUI_COMPONENT_EVENT_HPP
+#define FTXUI_COMPONENT_EVENT_HPP
+
+#include <vector>
+#include <array>
+
+namespace ftxui {
+
+struct Event{
+ public:
+  // --- Character ---
+  static Event Character(int);
+
+  // --- Arrow ---
+  static Event ArrowLeft;
+  static Event ArrowRight;
+  static Event ArrowUp;
+  static Event ArrowDown;
+  
+  // --- Other ---
+  static Event Backspace;
+  static Event Delete;
+  static Event Return;
+  static Event Escape;
+  static Event F1, F2, F3, F4, F5, F6, F7, F8, F9, F10, F11, F12;
+
+  // --- Custom ---
+  static Event Custom;
+
+  bool operator==(const Event& other) { return values == other.values; }
+
+  // Internal representation.
+  std::array<int, 5> values = {0, 0, 0, 0, 0};
+  
+};
+
+
+} // namespace ftxui
+
+
+#endif /* end of include guard: FTXUI_COMPONENT_EVENT_HPP */