Extend list filter operator to take a text reference

Instead of just a title. Means that we can apply the list operator to
fields other than the list field.

core/modules/filters/list.js

@@ -17,7 +17,8 @@ Export our filter function
 */
 exports.list = function(source,operator,options) {
 	var results = [],
-		list = options.wiki.getTiddlerList(operator.operand);
+		tr = $tw.utils.parseTextReference(operator.operand),
+		list = $tw.wiki.getTiddlerList(tr.title,tr.field,tr.index);
 	function checkTiddler(title) {
 		var match = list.indexOf(title) !== -1;
 		if(operator.prefix === "!") {

core/modules/wiki.js

@@ -611,10 +611,14 @@ exports.setTiddlerData = function(title,data) {
 /*
 Return the content of a tiddler as an array containing each line
 */
-exports.getTiddlerList = function(title) {
+exports.getTiddlerList = function(title,field,index) {
+	if(index) {
+		return $tw.utils.parseStringArray(this.extractTiddlerDataItem(title,index,""));
+	}
+	field = field || "list";
 	var tiddler = this.getTiddler(title);
-	if(tiddler && $tw.utils.isArray(tiddler.fields.list)) {
-		return tiddler.fields.list.slice(0);
+	if(tiddler) {
+		return ($tw.utils.parseStringArray(tiddler.fields[field]) || []).slice(0);
 	}
 	return [];
 };