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

This, along with the related VM pull request, fixes LLK/scratch-vm#865.
This adds the GUI code which posts wheel scroll data to the VM's
mouseWheel IO (which, in turn, activates relevant "when key pressed"
blocks).

* Implement GH-830: Add coming soon tooltips

This implements coming soon tooltips for:
* the small stage size
* save, load and language

It also creates the component that can be copied over into the paint editor for use there as well.

Lastly, this does a small refactor on the full screen implementation to include multiple small screen sizes too.

  1. Fixed issue with sprites not being dragable when stage zoomed.

  2. Fixed issue with coordinates of mouse position being wrong when
     stage is zoomed. This was caused by the renderer not being
     resized when zooming/unzooming.

  3. Refactored zoom control to separate react component/containter
     with global reducer for isZoomed, which is passed to the stage
     container. This allows for the zoom control to zoom the stage
     menu and stage as seperate containers.

  4. Added icons zoom/unzoom for stage zoom control. Moved icon
     position to be part of stage menu floating to right of start/stop
     buttons.

  * Needs a real icon for opening (borrowed sprite-info icon). The open
    icon needs to be moved from current location of underneath stage to
    same row as control buttons (start/stop vm).

  * The zoomed mode loses the ability to drag sprites. Haven't had
     a change to look into this yet.

This way a stage is not necessary for sound blocks to work

With jscodeshift thank God

* Set editing target when double clicking on sprite in stage

* rename double clicker handler and add comment

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.

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

* WIP: drag states in stage component

* WIP: Hacky drag canvas

* Update sprite position on drag

Use VM to put sprite into drag state and update the sprite's position while dragging.

Temporarily don't use the drawable data to drag a new canvas, this can happen whne we have somewhere to drag the sprite to.

`getBoundingClientRect` forces WebKit to recalculate the layout ("force reflow"), so cache the canvas bounding box rather than getting it on every mouse event.

The inline css method gives us nothing that CSS modules can't give us. This puts the project more in line with the way www works, and makes CSS actually readable.

Using class names gives us full control of the modal styles.