borrwoed a lot code from https://github.com/foriequal0/devterm_keyboard in order to optimize the trackball

Code/devterm_keyboard/state.ino

@@ -0,0 +1,36 @@
+#include <cassert>
+#include <algorithm>
+#include <limits>
+
+#include "state.h"
+
+State::State()
+  : fn(false),
+    middleClick(false)
+{
+}
+
+void State::tick(millis_t delta)
+{
+  middleClickTimeout.updateTime(delta);
+}
+
+void State::pressMiddleClick() {
+  middleClick = true;
+  middleClickTimeout.reset();
+}
+
+bool State::releaseMiddleClick() {
+  middleClick = false;
+  const auto timeout = middleClickTimeout.get();
+  return !timeout;
+}
+
+TrackballMode State::moveTrackball() {
+  middleClickTimeout.expire();
+  if (middleClick) {
+    return TrackballMode::Wheel;
+  } else {
+    return TrackballMode::Mouse;
+  }
+}