HT @paulkaplan

* Added localization for ‘Make a Block’
* ‘block name’ default text is in scratch-blocks

The changes in `error-step.jsx` were needed because the same id was defined in there and `unavailable_step.jsx`. The scripts to generate the json file for Transifex give an error if the same id is defined in two places. In error step it simply uses the id without redefining default value etc. The alternative would be to add a new messages.jsx file that has the definitions for shared text and include that in both places that use them.

Goes along with https://github.com/LLK/scratch-blocks/pull/1646

Provide a from target id when sharing blocks to another target so that variable conflicts can be resolved.

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.

- Make stage look more like a tile element and not flust with the stage info width.
- Make the stage select state more apparent

The onMouseUp handler for the menu rerenders the language menu before the select onChange function runs on Firefox. So it resets the language value back to the previous value and the locale doesn’t update. If the languageMenu isopen don’t fire the openlanguageMenu action.

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