Fixed crash on applying or changing settings

The m_page member used to access the widgets was deleted too early.
Deletion moved to finish() method.

src/plugins/coreplugin/generalsettings.cpp

@@ -77,7 +77,7 @@ QWidget *GeneralSettings::createPage(QWidget *parent)
             this, SLOT(resetExternalEditor()));
     connect(m_page->helpExternalEditorButton, SIGNAL(clicked()),
             this, SLOT(showHelpForExternalEditor()));
-    delete m_page;
+
     return w;
 }
 
@@ -88,6 +88,11 @@ void GeneralSettings::apply()
     EditorManager::instance()->setExternalEditor(m_page->externalEditorEdit->text());
 }
 
+void GeneralSettings::finish()
+{
+    delete m_page;
+}
+
 void GeneralSettings::resetInterfaceColor()
 {
     m_page->colorButton->setColor(0x666666);