Fix documentation typos

This patch fixes 2 simple typos in QGraphicsItem and QPainter
documentation and a copy/paste error between QAbstractItemModel's
beginRemoveColumns and beginRemoveRows documentation.

Change-Id: I32bdc4dc69154a40fe30a5b8c08d0c3a001853f8
Reviewed-by: Harri Porten <porten@froglogic.com>
Reviewed-by: Marc Mutz <marc.mutz@kdab.com>

src/corelib/itemmodels/qabstractitemmodel.cpp

@@ -3071,7 +3071,7 @@ void QAbstractItemModel::endRemoveColumns()
     When reimplementing a subclass, this method simplifies moving
     entities in your model. This method is responsible for moving
     persistent indexes in the model, which you would otherwise be
-    required to do yourself. Using beginMoveRows and endMoveRows
+    required to do yourself. Using beginMoveColumns and endMoveColumns
     is an alternative to emitting layoutAboutToBeChanged and
     layoutChanged directly along with changePersistentIndex.
 

src/gui/painting/qpainter.cpp

@@ -5968,7 +5968,7 @@ void QPainter::drawText(const QRect &r, int flags, const QString &str, QRect *br
     \snippet code/src_gui_painting_qpainter.cpp 17
     \endtable
 
-    The \a boundingRect (if not null) is set to the what the bounding rectangle
+    The \a boundingRect (if not null) is set to what the bounding rectangle
     should be in order to enclose the whole text. For example, in the following
     image, the dotted line represents \a boundingRect as calculated by the
     function, and the dashed line represents \a rectangle:

src/widgets/graphicsview/qgraphicsitem.cpp

@@ -4516,7 +4516,7 @@ void QGraphicsItem::setMatrix(const QMatrix &matrix, bool combine)
     otherwise, \a matrix \e replaces the current matrix. \a combine is false
     by default.
 
-    To simplify interation with items using a transformed view, QGraphicsItem
+    To simplify interaction with items using a transformed view, QGraphicsItem
     provides mapTo... and mapFrom... functions that can translate between
     items' and the scene's coordinates. For example, you can call mapToScene()
     to map an item coordiate to a scene coordinate, or mapFromScene() to map