PianoRoll: don't play test notes while recording

This is a partial revert of 2e799718d6.
As playing test notes generate MIDI events as well, they get recorded
like any other notes resulting in undesired behaviour.

Closes #368.

src/gui/piano_roll.cpp

@@ -1859,7 +1859,7 @@ void pianoRoll::testPlayNote( note * n )
 {
 	m_lastKey = n->key();
 	
-	//if( ! n->isPlaying() && ! m_recording && ! engine::getSong()->isPlaying() )
+	if( n->isPlaying() == false && m_recording == false )
 	{
 		n->setIsPlaying( true );
 		m_pattern->instrumentTrack()->pianoModel()->handleKeyPress( n->key(), n->midiVelocity() );