The initial commit for this was before we hooked up the community to redux.

This allows the project to continue playing/retain state while toggling language or player state.

And implement toggle on player playground

Fixes issue with changing language, and hopefully player/editor mode (untested).

This is for demonstration purposes, if this is the way we decide, I will make official APIs on the VM and the Renderer for checking for the canvas and renderer.

Using the new `ScratchMsgs.translate` function to generate localized menus and default values in the toolbox.

Locale detection function that checks browser setting and lets URL parameter (locale= or lang=) override the browser setting.

Use Blockly messages for category names in the default toolbox XML to allow the names to be localized from the Msgs table.

* updated locales reducer to include current messages and messagesByLocale (the previous all messages)
* moved locales out of gui
* include locales in the things exported by gui (index.js)

All thumbnail images have been updated. Titles have been edited, How To's have been reordered. Make A Clicker Game, video link was updated.

Add `?locale=<localecode>` to load in a new langage.
Add `?enable=language` to enable the language selector
Or combine the two: `?enable=language&locale=<localecode>`
Still accepts a hash, but requires that the hash be a sequence of digits.

Added new locales reducer to gui:
- initializes default  react-intl/localeData
- initializes default locale messages for all locales
- default locale is ‘en’ (can be overridden by URL)

Removed dependency on react-intl-redux, added ConnectedIntlProvider (uses correct locale messages from redux based on current locale)