* Bug in plugin Ordering
Comparing plugin A without a `plugin-priority` field to plugin B with a `plugin-priority= 1` results in the plugins being ordered B, A when it seems like they should be ordered A, B.
* Switch to setting a plugin-priority on the built in themes to allow overriding parts of them.
* Refactored control panel “Plugins” tab to make the elements more
reusable
* Refactored the display of plugin tiddlers to use the same format as
the control panel (as suggested, I think by @danielo515), adding the
shadow tiddler listing as an overridable extension tab
* Added a new tab in the “More” sidebar providing quick access to all
installed plugins
Although falling short of the proposal in #1976, this change makes the
sidebar tabs work much better with different colour page backgrounds
and background images.
* Moved “add new plugin” into a modal wizard
* Adopt big friendly buttons
* Add plugin icons and readmes to “add new plugin” modal
* Use tabs for splitting plugins/themes/languages
* Consistent styling between the “add new plugin” modal and the
“installed plugins” control panel tab
* Behind the scenes, moved from addressing the library as
`recipes/defaults/tiddlers/<etc>` to `recipes/library/tiddlers<etc>`
Layout bugs with position: sticky in Firefox mean that we probably
shouldn’t have sticky titles as the default. Rather than reverting to
putting them in a separate theme, it is proposed to expose the sticky
titles setting in Vanilla theme tweaks.
The trouble with the previous approach of storing several settings in a
single data tiddler was that it made it hard to introduce new settings.
Users who already have a custom copy of the settings/metrics tiddler
wouldn’t get the default settings. The new approach uses individual
tiddlers for each setting.
This commit also introduces a new theme tweak for the cutoff width for
switching between responsive views.
