Recording stats layout customizable.

Users can select the order, visibility and importance (primary or secondary) of all stats for recording layout from the Settings.
Also, users can select the number of columns per row in the recording layout: 1, 2 or 3.
Finally, show altitude/coordinate from settings have been removed (not needed anymore).
Fixes #659.
Fixes #302.
Fixes #820.

src/main/java/de/dennisguse/opentracks/viewmodels/StatisticData.java

@@ -0,0 +1,45 @@
+package de.dennisguse.opentracks.viewmodels;
+
+import android.util.Pair;
+
+import androidx.annotation.NonNull;
+
+import de.dennisguse.opentracks.content.data.DataField;
+
+public class StatisticData {
+    private final DataField dataField;
+    private final String value;
+    private final String unit;
+    private final String description;
+
+    public StatisticData(@NonNull DataField dataField, @NonNull Pair<String, String> valueAndUnit, String description) {
+        this.dataField = dataField;
+        this.value = valueAndUnit.first;
+        this.unit = valueAndUnit.second;
+        this.description = description;
+    }
+
+    public DataField getField() {
+        return dataField;
+    }
+
+    public String getValue() {
+        return value;
+    }
+
+    public boolean hasValue() {
+        return value != null;
+    }
+
+    public String getUnit() {
+        return unit;
+    }
+
+    public String getDescription() {
+        return description;
+    }
+
+    public boolean hasDescription() {
+        return description != null;
+    }
+}