Reset volume on boot

Although the secondary microcontroller remembers the volume, it doesn't apply it on boot.
We therefore need to set it once we receive the response to the get_volume call we make on boot in order to avoid it defaulting to a setting which may not be what the user wants.
This also fixes the "first button press doesn't trigger chime" issue / closes #13.

linp-doorbell.h

@@ -14,6 +14,7 @@ class LinpDoorbell : public Component, CustomAPIDevice {
  #ifdef LOG_SENSOR
   bool isChiming = false;
  #endif
+ bool hasSetVolume = false;
 
  public:
   #ifdef LOG_BINARY_SENSOR
@@ -77,6 +78,7 @@ class LinpDoorbell : public Component, CustomAPIDevice {
 
   void setup() override {
     Serial2.begin(115200);
+    hasSetVolume = false;
     commandQueue.enqueue("down get_volume");
     commandQueue.enqueue("down get_switch_list");
 
@@ -197,6 +199,15 @@ class LinpDoorbell : public Component, CustomAPIDevice {
     ESP_LOGI("linp-doorbell", "Param received: %s = %s", param.c_str(), value.c_str());
     #ifdef LOG_SENSOR
       if (param.equals("volume")) {
+      	if (!hasSetVolume) {
+      	  // Volume needs to be reset on boot to put it back to the last set value.
+      	  // This also jogs the doorbell to life so that it'll actually chime on first button press.
+      	  // If we don't do this, it won't chime on first press but will on subsequent presses.
+      	  int initialVolume = atoi(value.c_str());
+      	  ESP_LOGI("linp-doorbell", "Setting initial volume: %i", initialVolume);
+      	  hasSetVolume = true;
+      	  setVolume(initialVolume);
+      	}
         volume_sensor->publish_state(parse_float(value.c_str()).value());
       } else if (param.equals("switch_list")) {
         // Comma-separated list of button tunes.