Configure loaders so they operate on individual modules in scratch-*
dependencies.

scratch-gui exports `index.js` instead of just GUI container.

* 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

build in production mode on travis

Use absolute path when building library (production) so assets can be copied to /static in GUI consumer (like scratch-www)

- export image and sounds in dist/static/assets
- rename main export (`scratch-gui.js`, not `index.js`)
- move project-loader-hoc back to lib (VM doesn’t load properly without it)

export Library if `NODE_ENV===‘production’`, otherwise export playground and examples.

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

Instead of using svg-url-loader only

This reverts commit c177706a.

Still missing is a green flag, but blocks run!

Dynamic import didn’t do what we wanted, so just added `npm run i18n:msgs` to the start command. This is just temporary. Other changes as requested:
* exports in one place
* loc=> locale

Also fixed use of require for localeData to use dynamic import (this one works), so the babelrc changes are needed, otherwise import as a function is not recognized.

Generating the localization source to update the translation system (transifex) is really separate from building. When building we want to be using the current state of translations from transifex, and the english default strings are not needed.

Uses the babel-cli to run the babel-plugin-react-intl separately from  webpack.

Using babel-plugin-react intl to extract messages from sources that use react-intl. It creates one file per component, that’s not ideal for translators.

Transifex supports several different json formats. We picked the chrome i18n json format because it includes the ‘description’ and displays that to translators as instructions in the transifex UI.

It wasn't ever necessary. Still allow configuring this path in the GUI in case of different paths to static files for scratch-blocks.

Add missing file types to `.gitattributes`.
Use `node` instead of deprecated `stable` version specifier for Travis.
Set dev tool to `cheap-module-source-map`.

Using postcss-modules-values with imported values failed on our current basic usage; it is apparently not mature enough to be used yet.

The syntax used by postcss-simple-vars is already familiar to most people familiar with modern CSS build systems.

* Covers parts of these issues: GUI layout panes (#69), sprite libraries (#12), import buttons (#64), menu bar (#67), and sprite info area (#53)

~ Refactored layout pane structure by removing `display: flex` from `.box`, by default. Declaring flex instead only where specifically needed. This helped fix layout quirks, and should help us avoid hard to find issues related to nested flex boxes

~ Added descriptive classnames to boxes/containers/wrappers. Moved more padding, margins + layout into these wrappers to help with component reusability.

~ Set up a spacer unit variable inside `gui.css`, to start keeping consistent padding, margins and rounded corners between panes. Used [CSS/PostCSS Modules](https://github.com/css-modules/postcss-modules-values) to avoid SCSS dependency.

~ Refactored inline styles from JSX, into CSS files. 2 reasons: a) prepping for reuse of CSS Module variables. b) Feels easier to debug complex flex layouts when all the styles are in one place vs JS/HTML/CSS syntax mixed together

~ Added menu bar into layout via new component, and sprite info header in sprite selector pane, with stubs for the labels + forms. Sprite items are correctly scrolling, while leaving the header fixed, in Chrome. Mostly working in FFx. Not working in Safari, IE yet.

~ Style pass on library modal

~ Experimenting with a few different transition styles: Logo in menu bar, sprite library items, Add buttons.

Resolves #73

This improves React performance by skipping prop type checks and warnings

The previous method of configuring the port number was not cross-platform.  Resolves #20