Call updateToolbox whenever the blocks container updates and is visible so that changes to dynamic menus (e.g. costume renaming) are picked up. Update setLocale to call updateToolbox so that the toolboxRefresh gets re-enabled. This is needed for getting translated toolbox strings like 'Hello' and 'Hmmm...' to stay in sync with language changes.

Remove cruft and add comments to explain how setLocale is called.

In `blocks.jsx` only call setLocale if visible. Depends on `getLocale` being added to VM to know when global locale changed while not visible making the VM out of sync.

Fix rename variable bug by always passing additionalVars to the scratch-blocks prompt callback. Let scratch-blocks decide whether or not to use the additional vars based on whether the variable is local or global.

Depends on https://github.com/LLK/scratch-vm/pull/1321

Allow specifying variables as local vs. global. Pass var names from VM to scratch-blocks for checking for conflicts in all sprites when attempting to create a global var.

* 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)

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)

Also remove some obsolete code

* 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`