Add nautical miles (with feet for altitude).

Fixes #1280.

src/main/java/de/dennisguse/opentracks/data/models/Distance.java

@@ -29,6 +29,10 @@ public class Distance {
         return of(distance_mile * UnitConversions.MI_TO_M);
     }
 
+    public static Distance ofNauticalMile(double distance_mile) {
+        return of(distance_mile * UnitConversions.NAUTICAL_MILE_TO_M);
+    }
+
     public static Distance ofKilometer(double distance_km) {
         return of(distance_km * UnitConversions.KM_TO_M);
     }
@@ -51,6 +55,8 @@ public class Distance {
                 return Distance.ofKilometer(1);
             case IMPERIAL:
                 return Distance.ofMile(1);
+            case NAUTICAL_IMPERIAL:
+                return Distance.ofNauticalMile(1);
             default:
                 throw new RuntimeException("Not implemented");
         }
@@ -114,12 +120,18 @@ public class Distance {
         return toKM() * UnitConversions.KM_TO_MI;
     }
 
+    public double toNauticalMiles() {
+        return toKM() * UnitConversions.KM_TO_NAUTICAL_MILE;
+    }
+
     public double toKM_Miles(UnitSystem unitSystem) {
         switch (unitSystem) {
             case METRIC:
                 return toKM();
             case IMPERIAL:
                 return toMI();
+            case NAUTICAL_IMPERIAL:
+                return toNauticalMiles();
             default:
                 throw new RuntimeException("Not implemented");
         }
@@ -129,6 +141,7 @@ public class Distance {
         switch (unitSystem) {
             case METRIC:
                 return toM();
+            case NAUTICAL_IMPERIAL:
             case IMPERIAL:
                 return toFT();
             default:

src/main/java/de/dennisguse/opentracks/data/models/DistanceFormatter.java

@@ -46,6 +46,7 @@ public class DistanceFormatter {
                 case METRIC:
                     return new Pair<>(null, resources.getString(R.string.unit_meter));
                 case IMPERIAL:
+                case NAUTICAL_IMPERIAL:
                     return new Pair<>(null, resources.getString(R.string.unit_feet));
                 default:
                     throw new RuntimeException("Not implemented");
@@ -65,6 +66,12 @@ public class DistanceFormatter {
                 } else {
                     return new Pair<>(StringUtils.formatDecimal(distance.toFT(), decimalCount), resources.getString(R.string.unit_feet));
                 }
+            case NAUTICAL_IMPERIAL:
+                if (distance.greaterThan(Distance.ofNauticalMile(0.5))) {
+                    return new Pair<>(StringUtils.formatDecimal(distance.toNauticalMiles(), decimalCount), resources.getString(R.string.unit_nautical_mile));
+                } else {
+                    return new Pair<>(StringUtils.formatDecimal(distance.toFT(), decimalCount), resources.getString(R.string.unit_feet));
+                }
             default:
                 throw new RuntimeException("Not implemented");
         }

src/main/java/de/dennisguse/opentracks/data/models/Speed.java

@@ -93,6 +93,10 @@ public class Speed {
         return toKMH() * UnitConversions.KM_TO_MI;
     }
 
+    public double toKnots() {
+        return toKMH() * UnitConversions.KM_TO_NAUTICAL_MILE;
+    }
+
     public Duration toPace(UnitSystem unitSystem) {
         if (isZero()) {
             return Duration.ofSeconds(0);
@@ -106,6 +110,9 @@ public class Speed {
             case IMPERIAL:
                 distance *= UnitConversions.M_TO_MI;
                 break;
+            case NAUTICAL_IMPERIAL:
+                distance *= UnitConversions.M_TO_NAUTICAL_MILE;
+                break;
             default:
                 throw new RuntimeException("Not implemented");
         }
@@ -119,6 +126,8 @@ public class Speed {
                 return toKMH();
             case IMPERIAL:
                 return toMPH();
+            case NAUTICAL_IMPERIAL:
+                return toKnots();
             default:
                 throw new RuntimeException("Not implemented");
         }

src/main/java/de/dennisguse/opentracks/data/models/SpeedFormatter.java

@@ -47,6 +47,9 @@ public class SpeedFormatter {
             case IMPERIAL:
                 unitId = reportSpeedOrPace ? R.string.unit_mile_per_hour : R.string.unit_minute_per_mile;
                 break;
+            case NAUTICAL_IMPERIAL:
+                unitId = reportSpeedOrPace ? R.string.unit_knots : R.string.unit_minute_per_nautical_mile;
+                break;
             default:
                 throw new RuntimeException("Not implemented");
         }

src/main/java/de/dennisguse/opentracks/data/models/UnitConversions.java

@@ -53,6 +53,9 @@ public class UnitConversions {
     public static final double M_TO_MI = M_TO_KM * KM_TO_MI;
     // multiplication factor to convert meters to feet
     public static final double M_TO_FT = M_TO_MI * MI_TO_FT;
+    public static final double NAUTICAL_MILE_TO_M = 1852.0;
+    public static final double M_TO_NAUTICAL_MILE = 1 / NAUTICAL_MILE_TO_M;
+    public static final double KM_TO_NAUTICAL_MILE = 1000 * M_TO_NAUTICAL_MILE;
     // multiplication factor to convert meters per second to kilometers per hour
     public static final double MPS_TO_KMH = M_TO_KM / (S_TO_MIN * MIN_TO_HR);
     // multiplication factor to convert miles to km