Add a inline QVector::append(const QVector &) overload

This is present in QList already and its lack is a nuisance when
switching from QList based code to QVector (which makes sense e.g.
if the item size exceeds sizeof(void*))

Also, albeit operator+=() and operator<<() exist, some people
simply prefer functions with real function names.

[ChangeLog][QtCore][QVector] Added QVector::append(const QVector &) overload

Change-Id: I9aae8223b086765625f2f3071fab5da0780f8a43
Reviewed-by: Liang Qi <liang.qi@theqtcompany.com>
Reviewed-by: Olivier Goffart <ogoffart@woboq.com>

src/corelib/tools/qvector.cpp

@@ -463,6 +463,18 @@
     \sa operator<<(), prepend(), insert()
 */
 
+/*! \fn void QVector::append(const QVector<T> &value)
+
+    \overload
+
+    \since 5.5
+
+    Appends the items of the \a value vector to this vector.
+
+    \sa operator<<(), operator+=()
+*/
+
+
 /*! \fn void QVector::prepend(const T &value)
 
     Inserts \a value at the beginning of the vector.

src/corelib/tools/qvector.h

@@ -128,6 +128,7 @@ public:
     T &operator[](int i);
     const T &operator[](int i) const;
     void append(const T &t);
+    inline void append(const QVector<T> &l) { *this += l; }
     void prepend(const T &t);
     void insert(int i, const T &t);
     void insert(int i, int n, const T &t);

tests/auto/corelib/tools/qvector/tst_qvector.cpp

@@ -575,6 +575,18 @@ void tst_QVector::append() const
         QCOMPARE(v.last(), SimpleValue<T>::at(0));
     }
 #endif
+    {
+        QVector<int> v;
+        v << 1 << 2 << 3;
+        QVector<int> x;
+        x << 4 << 5 << 6;
+        v.append(x);
+
+        QVector<int> combined;
+        combined << 1 << 2 << 3 << 4 << 5 << 6;
+
+        QCOMPARE(v, combined);
+    }
 }
 
 void tst_QVector::appendInt() const