Add audible speed advisories

ios/Podfile.lock

@@ -1,4 +1,6 @@
 PODS:
+  - audio_session (0.0.1):
+    - Flutter
   - battery_plus (1.0.0):
     - Flutter
   - connectivity_plus (0.0.1):
@@ -122,6 +124,7 @@ PODS:
     - Flutter
 
 DEPENDENCIES:
+  - audio_session (from `.symlinks/plugins/audio_session/ios`)
   - battery_plus (from `.symlinks/plugins/battery_plus/ios`)
   - connectivity_plus (from `.symlinks/plugins/connectivity_plus/darwin`)
   - device_info_plus (from `.symlinks/plugins/device_info_plus/ios`)
@@ -163,6 +166,8 @@ SPEC REPOS:
     - Turf
 
 EXTERNAL SOURCES:
+  audio_session:
+    :path: ".symlinks/plugins/audio_session/ios"
   battery_plus:
     :path: ".symlinks/plugins/battery_plus/ios"
   connectivity_plus:
@@ -209,6 +214,7 @@ EXTERNAL SOURCES:
     :path: ".symlinks/plugins/wakelock_plus/ios"
 
 SPEC CHECKSUMS:
+  audio_session: 088d2483ebd1dc43f51d253d4a1c517d9a2e7207
   battery_plus: 1ff2e16ba75af2a78387f65476057a390b47885e
   connectivity_plus: ddd7f30999e1faaef5967c23d5b6d503d10434db
   device_info_plus: 97af1d7e84681a90d0693e63169a5d50e0839a0d

lib/ride/models/audio.dart

@@ -0,0 +1,15 @@
+enum SpeechRate {
+  fast,
+  normal,
+}
+
+extension SpeechRateDescription on SpeechRate {
+  String get description {
+    switch (this) {
+      case SpeechRate.fast:
+        return "Schnell";
+      case SpeechRate.normal:
+        return "Normal";
+    }
+  }
+}

lib/ride/models/recommendation.dart

@@ -14,6 +14,9 @@ class Recommendation {
   /// The predicted current signal phase, calculated periodically.
   final Phase calcCurrentSignalPhase;
 
+  /// The timestamp of the last recommendation.
+  final DateTime timestamp = DateTime.now();
+
   Recommendation(
       this.calcPhasesFromNow, this.calcQualitiesFromNow, this.calcCurrentPhaseChangeTime, this.calcCurrentSignalPhase);
 }