#134 on the fly custom class assign stops recording

[Avneesh Singh]

Steps:
1. start recording.
2. use F9.

result: recording is stopped.

analysis: it appeared in revision 3094.
The problem is in transport bar in following function
private void Presentation_Changed(object sender, urakawa.events.DataModelChangedEventArgs e)
{
if (mState != State.Stopped) Stop();
}