On discussion at Hangout #38 we felt that hiding them was confusing,
and that there were few situations where a user would see system tags
except on system tiddlers.
Now the ViewTemplate just renders the current tiddler through each
template tagged `$:/tags/ViewTemplate`. This allows plugins (and users)
to add/remove elements from the ViewTemplate easily, without
overwriting the ViewTemplate itself.
(For @giffmex)
