Fixes for translators edition/plugin

* Added support for translating the core readme
* Fixed problem with `Misc.multids` rendering shadow tiddlers
* Fixed problem with single tiddler files rendering shadow tiddlers
Stop translated strings moving in the list

Without sorting the list, we had ordinary tiddlers listed before shadow
tiddlers. That meant that as soon as you started to type in a shadow
tiddler it moved up in the list.
Add unpackplugin command

Needed for the translators edition
Update extracting translations docs
Docs tiddler for editions command

We duplicate the command help tiddlers so that we can tag them.
Updated Japanese translation
Use bordered flags for ja-JP and ru-RU

The borderless images don’t show up well in the menu
Increase size of flags in language dropdown