Merge pull request #489 from BramChen/master

Keep up-to-date changes for zh-Hant and zh-Hans
Add a class to tiddler frames in view mode

We’re already marking tiddlers in edit mode with tw-tiddler-edit-mode,
makes sense to make view mode tiddlers too.
Extend button widget to set text references

Previously the `set` attribute could only be used to identify a
tiddler, not a full text reference.
Add a warning segment to templates for TWC tiddlers

Now there’s a warning banner on all TWC tiddlers. It includes an
`upgrade` button that currently just flips the tiddler type to TW5
Remove whitespace between toolbar icons
Starting to make the members of $tw.Wiki be private

We want to avoid plugins from directly accessing the tiddlers hashmap.
Later we’ll do pluginTiddlers, pluginInfo and shadowTiddlers.
Freeze array or object tiddler fields

Previously object fields like the tags array weren’t frozen.