Refactor user interface for plugin tiddlers

* 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

core/ui/MoreSideBar/Plugins.tid

@@ -0,0 +1,8 @@
+title: $:/core/ui/MoreSideBar/Plugins
+tags: $:/tags/MoreSideBar
+caption: {{$:/language/ControlPanel/Plugins/Caption}}
+
+
+{{$:/language/ControlPanel/Plugins/Installed/Hint}}
+
+<<tabs "[all[shadows+tiddlers]tag[$:/tags/MoreSideBar/Plugins]!has[draft.of]]" "$:/core/ui/MoreSideBar/Plugins/Plugins">>

core/ui/MoreSideBar/plugins/Languages.tid

@@ -0,0 +1,5 @@
+title: $:/core/ui/MoreSideBar/Plugins/Languages
+tags: $:/tags/MoreSideBar/Plugins
+caption: {{$:/language/ControlPanel/Plugins/Languages/Caption}}
+
+<$list filter="[!has[draft.of]plugin-type[language]sort[description]]" template="$:/core/ui/PluginListItemTemplate" emptyMessage={{$:/language/ControlPanel/Plugins/Empty/Hint}}/>

core/ui/MoreSideBar/plugins/Plugins.tid

@@ -0,0 +1,5 @@
+title: $:/core/ui/MoreSideBar/Plugins/Plugins
+tags: $:/tags/MoreSideBar/Plugins
+caption: {{$:/language/ControlPanel/Plugins/Plugins/Caption}}
+
+<$list filter="[!has[draft.of]plugin-type[plugin]sort[description]]" template="$:/core/ui/PluginListItemTemplate" emptyMessage={{$:/language/ControlPanel/Plugins/Empty/Hint}}>>/>

core/ui/MoreSideBar/plugins/Theme.tid

@@ -0,0 +1,5 @@
+title: $:/core/ui/MoreSideBar/Plugins/Theme
+tags: $:/tags/MoreSideBar/Plugins
+caption: {{$:/language/ControlPanel/Plugins/Themes/Caption}}
+
+<$list filter="[!has[draft.of]plugin-type[theme]sort[description]]" template="$:/core/ui/PluginListItemTemplate" emptyMessage={{$:/language/ControlPanel/Plugins/Empty/Hint}}/>