Create setting for default type of draft tiddlers (#8783)

* Proof of concept to change type of tiddlers created by editing missing.

* Adding a setting for default type so that it can be overridden for other wikis.

* Incorporating PR feedback.

* Adding documentation tiddler for new setting.

* Added documentation to the markdown plugin documentation.

* Added documentation to the markdown plugin documentation.

* Added notice to markdown edition.

core/modules/widgets/navigator.js

@@ -277,6 +277,8 @@ NavigatorWidget.prototype.makeDraftTiddler = function(targetTitle) {
 	}
 	// Get the current value of the tiddler we're editing
 	var tiddler = this.wiki.getTiddler(targetTitle);
+	var defaultType = this.wiki.getTiddlerText("$:/config/DefaultMissingType", "").trim();
+	var defaultFields = { type: defaultType };
 	// Save the initial value of the draft tiddler
 	draftTitle = this.generateDraftTitle(targetTitle);
 	var draftTiddler = new $tw.Tiddler({
@@ -288,7 +290,8 @@ NavigatorWidget.prototype.makeDraftTiddler = function(targetTitle) {
 				"draft.title": targetTitle,
 				"draft.of": targetTitle
 			},
-			this.wiki.getModificationFields()
+			this.wiki.getModificationFields(),
+			tiddler === null || tiddler === undefined ? defaultFields : {}
 		);
 	this.wiki.addTiddler(draftTiddler);
 	return draftTiddler;