This use of shouldComponentUpdate is wrapping the incorrect use of bind
in the mapStateToProps call.

I also suspect this will fix some of the times when the menu
mysteriously stayed open, because it was being re-rendered for by
mistake.

This makes it possible to use on iOS/touch

Add duplicate button. Pass the costume ID to paint (the previous costume ID used matches when duplicate is used.) When switching to the costume tab, open the current costume.

This is required because you can delete the last sound, and without a re
render the tab will continue to render the sound editor, causing an
error.

- Call scrollToCategoryByName('My Blocks') after custom block is created
- Cannot assume custom blocks section will be last category
- May pose issue during localization efforts

Use the same drag threshold as from the blocks. It may need to be dialed
in further, but testing will be needed.

Images are draggable by default, but when used within buttons or as
clickable elements, they should not be draggable because starting a drag
accidentally prevents the click event.

Since we will be adding more interactivity, the active state will
eventually pop the menu open, so I'm not worried about accessibility of
this right now.