Previously, raw markup tiddlers were being saved even if they weren't included in the saveTiddlerFilter. This meant that, for example, using "save empty" button in GettingStarted would include the splash screen markup tiddler.
These tiddlers were being handled as `<script>` tags to make it easier
to debug them. But in fact modern dev tools are quite happy to debug
code that has been eval’d, and this arrangement was causing problems
for importing.
Fixes#335
We’re introducing a mechanism that allows us to decide which tiddlers
get saved. Using `$:/core/save/all` gives all tiddlers, as before.
Using `$:/core/save/empty` gives an empty wiki. Saving an empty wiki
from tw5.com isn’t the same as the empty wiki cooked from
editions/empty because the two editions have different plugins and
other system tiddlers.
