AutomatableModel: fix wrong comparison logic

We must not negate the float but instead test for inequality in order to
determine whether the linked model has to be updated.

Closes #1761.

src/core/AutomatableModel.cpp

@@ -318,8 +318,7 @@ void AutomatableModel::setAutomatedValue( const float value )
 									it != m_linkedModels.end(); ++it )
 		{
 			if( (*it)->m_setValueDepth < 1 &&
-				!(*it)->fittedValue( m_value ) !=
-							 (*it)->m_value )
+				(*it)->fittedValue( m_value ) != (*it)->m_value )
 			{
 				(*it)->setAutomatedValue( value );
 			}