With jscodeshift thank God

* Set editing target when double clicking on sprite in stage

* rename double clicker handler and add comment

* Fix costume loading in sprite info pane

Requires LLK/scratch-vm#517

* Fix costume loading in costumes tab

Requires LLK/scratch-vm#517

Attaching the storage module in `vmListenerHOC` means it can propagate
down to the GUI, stage, and blocks naturally. The default VM property
value has been removed from those places so that we're not instantiating
extra VM instances any more. Instead, using one of those components
outside of the `vmListenerHOC` framework will require providing a VM
instance as a property.

Remove target pane button and actions

Add back putting the sound library in the ui

There are a handful of places where the GUI code could use the storage
module directly; converting those is for a later change.

Fixes #156 + refactored classnames to style guide conventions

Affects SpriteSelector Pane, StageSelector Pane, Stage, MenuBar, Libraries Modal, Add/Import buttons, for Chrome, Ffx + Safari on Sierra.

Fixes #162

* Update blocks.js

Fixes #220