AggregatedStatisticsActivity: added filter option (by category, start and/or end date).

Fixes #1039.

src/main/java/de/dennisguse/opentracks/content/provider/SelectionData.java

@@ -0,0 +1,24 @@
+package de.dennisguse.opentracks.content.provider;
+
+public class SelectionData {
+    private final String selection;
+    private final String[] selectionArgs;
+
+    public SelectionData() {
+        selection = null;
+        selectionArgs = null;
+    }
+
+    public SelectionData(String selection, String[] selectionArgs) {
+        this.selection = selection;
+        this.selectionArgs = selectionArgs;
+    }
+
+    public String getSelection() {
+        return selection;
+    }
+
+    public String[] getSelectionArgs() {
+        return selectionArgs;
+    }
+}