Fixed spelling errors

Fixed some spelling errors found by Lintian while checking the Debian
package of LMMS. Thanks to Patrick Winnertz for pointing out this issue.
(cherry picked from commit 9fd3dacb67)

src/core/AutomatableModel.cpp

@@ -139,7 +139,7 @@ void AutomatableModel::loadSettings( const QDomElement & _this,
 			p->loadSettings( node.toElement() );
 			setValue( p->valueAt( 0 ) );
 			// in older projects we sometimes have odd automations
-			// with just one value in - eliminate if neccessary
+			// with just one value in - eliminate if necessary
 			if( !p->hasAutomation() )
 			{
 				delete p;

src/core/audio/AudioDevice.cpp

@@ -89,7 +89,7 @@ fpp_t AudioDevice::getNextBuffer( surroundSampleFrame * _ab )
 	// make sure, no other thread is accessing device
 	lock();
 
-	// resample if neccessary
+	// resample if necessary
 	if( getMixer()->processingSampleRate() != m_sampleRate )
 	{
 		resample( b, frames, _ab, getMixer()->processingSampleRate(),

src/core/midi/MidiClient.cpp

@@ -265,7 +265,7 @@ void MidiClientRaw::processOutEvent( const midiEvent & _me,
 							const midiTime & ,
 							const MidiPort * _port )
 {
-	// TODO: also evaluate _time and queue event if neccessary
+	// TODO: also evaluate _time and queue event if necessary
 	switch( _me.m_type )
 	{
 		case MidiNoteOn:

src/core/mixer.cpp

@@ -678,7 +678,7 @@ const surroundSampleFrame * mixer::renderNextBuffer()
 
 
 
-// removes all play-handles. this is neccessary, when the song is stopped ->
+// removes all play-handles. this is necessary, when the song is stopped ->
 // all remaining notes etc. would be played until their end
 void mixer::clear()
 {

src/core/song.cpp

@@ -338,7 +338,7 @@ void song::processNextBuffer()
 		return;
 	}
 
-	// check for looping-mode and act if neccessary
+	// check for looping-mode and act if necessary
 	timeLine * tl = m_playPos[m_playMode].m_timeLine;
 	bool check_loop = tl != NULL && m_exporting == false &&
 				tl->loopPointsEnabled() &&

src/core/track.cpp

@@ -1,5 +1,5 @@
 /*
- * track.cpp - implementation of classes concerning tracks -> neccessary for
+ * track.cpp - implementation of classes concerning tracks -> necessary for
  *             all track-like objects (beat/bassline, sample-track...)
  *
  * Copyright (c) 2004-2009 Tobias Doerffel <tobydox/at/users.sourceforge.net>

src/gui/automation_editor.cpp

@@ -223,7 +223,7 @@ automationEditor::automationEditor() :
 			"'Shift+E' on your keyboard to activate this mode." ) );
 	m_selectButton->setWhatsThis(
 		tr( "Click here and select-mode will be activated. In this "
-			"mode you can select values. This is neccessary "
+			"mode you can select values. This is necessary "
 			"if you want to cut, copy, paste, delete, or move "
 			"values. You can also press 'Shift+S' on your keyboard "
 			"to activate this mode." ) );

src/gui/widgets/InstrumentSoundShapingView.cpp

@@ -58,7 +58,7 @@ InstrumentSoundShapingView::InstrumentSoundShapingView( QWidget * _parent ) :
 	m_targetsTabWidget->setWhatsThis(
 		tr( "These tabs contain envelopes. They're very important for "
 			"modifying a sound, in that they are almost "
-			"always neccessary for substractive synthesis. For "
+			"always necessary for substractive synthesis. For "
 			"example if you have a volume envelope, you can set "
 			"when the sound should have a specific volume. "
 			"If you want to create some soft strings then your "