Attempt to externalize plugins

This TiddlyWiki contains the following tiddlers:

$:/config/AutoSave
$:/config/externalURL/$:/plugins/theophile.dev/inplace-upgrade
$:/config/externalURL/$:/plugins/theophile.dev/nav
$:/config/inplace-upgrade/core-url
$:/config/inplace-upgrade/target-url
$:/config/SaveWikiButton/Template
$:/GitHub/Filename
$:/GitHub/Path
$:/GitHub/Repo
$:/GitHub/Username
$:/Import
$:/isEncrypted
$:/plugins/theophile.dev/external-plugins/ControlPanel
$:/SiteDomain
$:/SitePreviewUrl
$:/SiteTitle
$:/SiteUrl
$:/state/advancedsearch/currentTab
$:/state/http-requests
$:/state/plugin-info-551182168-$:/plugins/theophile.dev/inplace-upgrade--720658648
$:/state/showeditpreview
$:/state/sidebar
$:/state/tab--1498284803
$:/state/tab-1749438307
$:/state/tab-2065006209
$:/state/tab/sidebar--595412856
$:/status/IsLoggedIn
$:/status/RequireReloadDueToPluginChange
$:/StoryList
$:/themes/tiddlywiki/snowwhite
$:/themes/tiddlywiki/vanilla
$:/UploadURL
$:/UploadWithUrlOnly
Draft of 'externalize'
externalize

add-button-actions,add-tag-actions,background-linear-gradient,box-shadow,branch-node,button-export-external-plugin,change-input-tab,clear-tags-actions,clear-tags-actions-inner,color,colour,colour-picker,colour-picker-inner,colour-picker-recent,colour-picker-recent-inner,colour-picker-update-recent,column-count,compareTiddlerText,compareTiddlers,condition,copy-to-clipboard,copy-to-clipboard-above-right,coreURL,currentTiddler,datauri,defaultCoreURL,delete-tag-state-tiddlers,dumpvariables,edit-external-url,exportButton,exportButtonFilename,filename,filter,if-background-attachment,if-no-sidebar,if-sidebar,image-picker,image-picker-include-tagged-images,image-picker-list,image-picker-thumbnail,input-next-actions-after,input-next-actions-before,input-next-actions-inner,keyboard-driven-input,keyboard-input-actions,leaf-link,leaf-node,lingo,lingo-base,list-links,list-links-draggable,list-links-draggable-drop-actions,list-tagged-draggable,list-tagged-draggable-drop-actions,list-thumbnails,mark-external,missingTiddlerClass,plugin.URL,plugins.externalized,prefix.bracket,publishFilter,rawMarkupFilter,saveTiddlerAndShadowsFilter,saveTiddlerFilter,shadowTiddlerClass,show-filter-count,suffix.bracket,systemTiddlerClass,tabs,tabs-button,tabs-tab,tabs-tab-body,tabs-tab-list,tag,tag-picker,tag-picker-inner,tag-picker-listTags,tag-pill,tag-pill-body,tag-pill-inner,tag-pill-styles,template-external-plugin,testcase,tf.change-input-tab.next-tab,tf.get-tagpicker-focus-selector,tf.tagpicker-dropdown-class,tf.tagpicker-dropdown-id,thisTiddler,thumbnail,thumbnail-right,tiddlerTagClasses,timeline,timeline-link,timeline-title,toc,toc-body,toc-caption,toc-closed-icon,toc-expandable,toc-expandable-empty-message,toc-level-indicator,toc-linked-expandable-body,toc-linked-selective-expandable-body,toc-open-icon,toc-selective-expandable,toc-selective-expandable-empty-message,toc-tabbed-external-nav,toc-tabbed-internal-nav,toc-unlinked-expandable-body,toc-unlinked-selective-expandable-body,transclusion,transform-origin,transition,translink,tree,tree-node