MainWindow: removed HQ mode button

Switching to HQ mode in standard workflow doesn't make much sense and
is likely to cause problems. Therefore remove the HQ mode button for
for time being. One can still export projects in high(er) quality.
(cherry picked from commit d66c71ebf8)

src/gui/song_editor.cpp

@@ -117,10 +117,9 @@ songEditor::songEditor( song * _song, songEditor * & _engine_ptr ) :
 			"should be played within a minute (or how many measures "
 			"should be played within four minutes)." ) );
 
-	int col = engine::getMainWindow()->addWidgetToToolBar( m_tempoSpinBox,
-									0 );
-
+	engine::getMainWindow()->addWidgetToToolBar( m_tempoSpinBox, 0 );
 
+#if 0
 	toolButton * hq_btn = new toolButton( embed::getIconPixmap( "hq_mode" ),
 						tr( "High quality mode" ),
 						NULL, NULL, tb );
@@ -129,7 +128,7 @@ songEditor::songEditor( song * _song, songEditor * & _engine_ptr ) :
 			this, SLOT( setHighQuality( bool ) ) );
 	hq_btn->setFixedWidth( 42 );
 	engine::getMainWindow()->addWidgetToToolBar( hq_btn, 1, col );
-
+#endif
 
 	engine::getMainWindow()->addSpacingToToolBar( 10 );