Fix various qdoc-warnings.

qtbase/src/corelib/itemmodels/qitemselectionmodel.cpp:1199: warning: Undocumented parameter 'model' in QItemSelectionModel::modelChanged()
qtbase/src/corelib/plugin/qpluginloader.cpp:420: warning: Can't link to 'staticPlugin()'
qtbase/src/gui/text/qtextdocument.cpp:1452: warning: No such parameter 'from' in QTextDocument::find()
qtbase/src/testlib/qtestcase.cpp:2770: warning: No documentation for 'QTest::qExtractTestData()'

Change-Id: I76758dbdf3ad7b0ae1f14de0407a6fde523827d0
Reviewed-by: Konstantin Ritt <ritt.ks@gmail.com>

src/corelib/itemmodels/qitemselectionmodel.cpp

@@ -1200,7 +1200,7 @@ void QItemSelectionModel::select(const QModelIndex &index, QItemSelectionModel::
     \fn void QItemSelectionModel::modelChanged(QAbstractItemModel *model)
     \since 5.5
 
-    This signal is emitted when the model is successfully set with setModel().
+    This signal is emitted when the \a model is successfully set with setModel().
 
     \sa model(), setModel()
 */

src/corelib/plugin/qpluginloader.cpp

@@ -420,7 +420,7 @@ void Q_CORE_EXPORT qRegisterStaticPluginFunction(QStaticPlugin plugin)
 /*!
     Returns a list of static plugin instances (root components) held
     by the plugin loader.
-    \sa staticPlugin()
+    \sa staticPlugins()
 */
 QObjectList QPluginLoader::staticInstances()
 {

src/gui/text/qtextdocument.cpp

@@ -1453,7 +1453,7 @@ QTextCursor QTextDocument::find(const QRegExp & expr, int from, FindFlags option
     \overload
 
     Finds the next occurrence, matching the regular expression, \a expr, in the document.
-    The search starts at the position of the given \a from cursor, and proceeds
+    The search starts at the position of the given from \a cursor, and proceeds
     forwards through the document unless specified otherwise in the search
     options. The \a options control the type of search performed. The FindCaseSensitively
     option is ignored for this overload, use QRegExp::caseSensitivity instead.