The new importvariables widget imports macro/variable definitions from
the specified tiddlers and makes them available to its children.
Allows us to split PageMacros up into separate tiddlers.
We still support loading macros from $:/core/ui/PageMacros to help
people upgrading.
Fixes#644 and #559
A bunch of little changes that together enable external image support.
Try:
```
tiddlywiki editions/tw5.com --verbose --build externalimages
```
Then open `externalimages.html`, look for the images in the more/types
tab of the sidebar, open them and verify that they are set with an
external SRC attribute, not a data URI.
Now a link to a single tiddler like http://tiddlywiki.com/#HelloThere
will just open that single tiddler (the old behaviour was to also open
the default tiddlers)
Previously, widgets were reading variables from themselves or their
cascaded ancestors. That means that if a widget sets a variable and
then reads the same variable, it will get the same variable back. That
sounds reasonable, until you consider a widget that wants to modify a
variable - eg the tiddler macro. For example:
```
<$tiddler tiddler={{!!report}}>
<$transclude mode="block" />
</$tiddler>
```
Here we first evaluate the `{{!!report}}` reference, which involves
reading the currentTiddler variable, looking up the tiddler, and
retrieving it’s `report` field. The next the tiddler widget is
refreshed, it will use the newly set currentTiddler as the basis for
resolving the `{{!!reference}}` reference.
The fix is to get variables from ancestors, but continue to set them on
ourselves.
We were parsing the boot tiddlers, making them into a widget and then
refreshing the widget tree. The problem is that subsequent chances to
the boot tiddlers themselves wouldn’t be picked up as part of the
refresh.
Now we indirectly parse those UI boot tiddlers through a transclusion,
which does get refreshed in the desired way.
Now we respond dynamically to changes in the location hash in the URL
bar. It means that you can do links in HTML as `<a
href=“#HelloThere”>go</a>` and in Markdown as `[example
link](#HelloThere).`
We still need to make startup.js more modular
Jermolene