add back indent guide, misc tweaks

mainwindow.h

@@ -31,8 +31,8 @@ private:
     void setupActions();
     void showSettings();
     void applyLexer(const QString & lexer);
-    void applySettingsToEditor(SciEdit *editor);
-    void applySettingsToAllEditors();
+    void applySettingsToEditor(SciEdit *editor);
+    void applySettingsToAllEditors();
     void updateWindowTitle();
     void updateStatusBar();
     void updateActions();
@@ -42,6 +42,7 @@ private:
     QLabel *m_cursorPosStatusLabel;
     QLabel *m_encodingStatusLabel;
     QLabel *m_languageStatusLabel;
+    bool m_indentGuidesEnabled = false;
 };
 
 // plainly for KConfigDialog