- Add new ESP-NOW mesh backend.

- Add HelloEspnow.ino example to demonstrate the ESP-NOW mesh backend features.

- Deprecate the ESP8266WiFiMesh class in favour of the new ESP-NOW and TCP/IP backends.

- Update the TCP/IP mesh backend to use the new lwIP version preprocessor flag and remove obsolete preprocessor flags.

libraries/ESP8266WiFiMesh/src/ExpiringTimeTracker.cpp

@@ -0,0 +1,59 @@
+/*
+ * Copyright (C) 2019 Anders Löfgren
+ *
+ * License (MIT license):
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "ExpiringTimeTracker.h"
+
+ExpiringTimeTracker::ExpiringTimeTracker(uint32_t duration, uint32_t creationTimeMs) :
+  TimeTracker(creationTimeMs), _duration(duration)
+{ }
+
+uint32_t ExpiringTimeTracker::duration() const
+{
+  return _duration;
+}
+
+void ExpiringTimeTracker::setRemainingDuration(uint32_t remainingDuration)
+{
+  _duration = timeSinceCreation() + remainingDuration;
+}
+
+uint32_t ExpiringTimeTracker::remainingDuration() const
+{
+  uint32_t remainingDuration = duration() - timeSinceCreation();
+  
+  if(expired())
+  {
+    // Overflow probably occured for remainingDuration calculation.
+    return 0;
+  }
+  else
+  {
+    return remainingDuration;
+  }
+}
+
+bool ExpiringTimeTracker::expired() const
+{
+  return timeSinceCreation() > duration();
+}