Planner: fix an enduring assert on startup

qt 5.3, win7 64bit.

beginRemoveRows() asserts in removeSelectedPoints()
because rowCount() - 1, becomes less than firstRow.

This needs a check in removeSelectedPoints() if the number
of passed rows is zero.

Signed-off-by: Lubomir I. Ivanov <neolit123@gmail.com>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>

qt-ui/diveplanner.cpp

@@ -53,6 +53,8 @@ bool intLessThan(int a, int b)
 }
 void DivePlannerPointsModel::removeSelectedPoints(const QVector<int> &rows)
 {
+	if (!rows.count())
+		return;
 	int firstRow = rowCount() - rows.count();
 	QVector<int> v2 = rows;
 	std::sort(v2.begin(), v2.end(), intLessThan);