Cleaned up undo library file
Increased undo limit in UI from 32 to 100
DListBoxItem now properly checks its IsSelected() state for drawing selected state rather than relying on DListBox not having mutliple selections and testing whether the selected item has the same text as its own text
Community Contributions:
* math.Clamp nano optimisation
* VectorRand and AngleRand now have optional min and max arguments