v0.4.2

• Added color presets to scribble: press 0 through 9 while drawing to
  quickly toggle through a preset color palette, customizable using the
  palette argument of use_palette() (thanks @kim-soo-hwan, #112, #117).

• New feature: animated progress bars that don't interfere with the slide
  number. Simply add use_progress_bar() to your slides! (#109, #118)