Move guiMiddleware to `reducers/gui.js`, and use it in `app-state-hoc`

* Export initial states for each reducer
* combine all gui reducers (excludes scratchPaint and intl)
* combine all initial states to create default guiState for preloading in www
* expect all of the gui state to be accessible at `state.scratchGui`

* Player mode

Add isPlayerOnly property on GUI. Move isFullScreen into mode reducer with isPlayerOnly.

Full screen needs to be a separate prop so that GUI knows what to show when exiting full-screen (either player-only or full editor).

- set `gui-body * {box-sizing: border-box;}` instead of expecting it to be set by the enclosing component/playground, and removed uses of content-box (adjusting sizes as needed) 
- Added `!isPlayerOnly` to the conditions for draggable sprites
- rewrote player example to use player mode.

Prevent crashes resulting from the editing target not being on the target list.

This reverts commit 29d5619d.

* WIP tips

* WIP first card stack

* WIP use tips reducer to show things to try

* single card deck similar to mask sequence

* collapse option

* Add zoom card

* WIP tips

* Reorganized to redux

* Add zooming to the gifs

* Blue cards + navigation

* Add tips to new nav bar

* Remove blue

* Update design with icons

* deck updates wip

* Updated card decks

* Add videos to libraries

* Update initial card and clicker preview

* Add backdrop to initial card step.

* WIP use vimeo player instead

* New simple spin deck

* Spin around and say hello decks

* Update button and sub-card styles

* Fix "tips" button in menu bar

* Use move cursor

* Fix cursor

* Use same image for deck preview and library

* Fix cursor again

* Update clicker game deck

* Add videos as single-step decks

* Change tips in menu bar to ? icon

* Change “tips” to “how-tos” in library

* Add help icon to cards

* Update deck library images

* Add drag cover for youtube video to prevent catching mouseup

* add a step to spin deck for clicking control

* Blue bar style updates

* Add step pips

* Update clicker game name to run away

* Fix image padding

* Add change color step to spin deck

* Add start sound step to run away deck

* Update say deck to start with adding a sprite

* Remove package lock

* Remove zooming functionality

* Remove unnecassary prototype changes

* Split up rendering of cards into smaller parts

* Use FormattedMessage for all strings

* Automatic lint fixes

* Almost finished with lint errors!

* Fix more lint errors

* Clean up CSS

* Fix webpack config

* Updates to preview modal for release

* Design tweaks and remove import modal

* Resolve issues with tests

* Copy edits HT Eric

* Resolve lint issue with integration test

* One more change to the disclaimer language

* Add line break

Allow intl to be passed in to GUI as a prop (rather than having to be already in the store)

whoops

They open and close what more do you want?

Revert "Changes to hash should happen through project loader hoc. Changes to the current project id and current project data should happen in a reducer since they are part of global state. That way, the load button can affect the global project data as well."

This reverts commit e4fe143b.

Changes to hash should happen through project loader hoc. Changes to the current project id and current project data should happen in a reducer since they are part of global state. That way, the load button can affect the global project data as well.

Initial SB2 Import UI (button in preview modal + import modal that can load projects via url). Preliminary validation on url, still needs error handling.

* add feedback form

This implements #829

* small style updates to the stage buttons

from @carljbowman

* remove `stageSize` for now

We eventually need this, but not yet, and it’s causing lint failure.

- implements welcome to the preview modal, and unsupported browser modal.
- will need assets updated in Jan.

* 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.

Localizes the pen extension:
- loads all pen locale information - may want to consider dynamically loading locales later.

This way the instance can be reused, which allows access to non-deprecated `DataFormat` and `AssetType`.

Uses new version of scratch-l10n.

* removed anything that was made redundant by scratch-l10n.
* updated a string that wasn’t following conventions
* added .tx/config so developers can start updating Transifex when there are new strings