message: Add keyboard shortcuts for selecting the current painting tool
  Now uses
  'x' - draw
  'c' - colorize
  'b' - select brush
  But '1', '2', '3', '4' might feel better for these actually.
diff: @@ -80,6 +80,12 @@ export class Toolbar {
  dispatch(Toolbar.actions.nextColor(-1))
  } else if (key === 'e') {
  dispatch(Toolbar.actions.nextColor(+1))
  + } else if (key === 'x') {
  + dispatch(Toolbar.actions.setSelectedTool(TOOL_DRAW))
  + } else if (key === 'c') {
  + dispatch(Toolbar.actions.setSelectedTool(TOOL_COLORIZE))
  + } else if (key === 'b') {
  + dispatch(Toolbar.actions.setSelectedTool(TOOL_BRUSH))
  }
  }
  