Improve handling of commands embedded in midi files

[kitlith]

GotaSequenceLib/SMF.cs

Lines 911 to 918 in c2c0510

	if (dat.Contains(": ")) {
	try {
	SequenceCommand c = new SequenceCommand(); //THIS DOES NOT TAKE CARE OF JUMPS AS IT WILL JUMP TO THE MARKER TRACK.
	if (int.Parse(dat.Split(':')[0]) == trackNum) {
	c.FromString(dat.Substring(dat.IndexOf(":") + 2), labels, new Dictionary<string, int>());
	commands.Add(c);
	}
	} catch { }

Ideally, this feature would:

• Support jumps (referring to the comment, but i'm not really sure what it's talking about)
  • I'm not sure what the comment is on about, because it already seems to work fine (though it might not work if the label is located after the jump instruction)
  • I think I understand now. Some editors dump all markers onto a single track (or idk, maybe some dump on all of them?), and jumps only work if markers can be placed on specific tracks.
    • for that matter though, i think the command insertion only properly works if the marker is on the specific track as well -- it just doesn't insert the command if it's the wrong track.
• Support multiple commands in a single marker (for i.e. a conditional jump cmp_eq 14, 10000; jump_if LS0)
• Not require you to list the track number -- it's already in the middle of the track. (is there varying behavior by different midi editors?)
• Support mentioning labels that occur after the current marker.

Random idea is to also support 'this command goes on every track' markers on track 0 with the ability to insert the current track number into the command somewhere. (this would essentially be a more powerful version of the commented out looping functionality)