Simple test case for merging dives

We do some merging in a couple of the other tests as well, but the idea
is to have specific test cases that exercise our merge logic.

This one starts simple. Merge a dive with some valid info with a second
one that has less data filled. And then try it in both possible orders.

It shows a few potential problems.

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>

tests/testmerge.h

@@ -0,0 +1,14 @@
+#ifndef TESTMERGE_H
+#define TESTMERGE_H
+
+#include <QtTest>
+
+class TestMerge : public QObject{
+	Q_OBJECT
+private slots:
+	void initTestCase();
+	void testMergeEmpty();
+	void testMergeBackwards();
+};
+
+#endif