Add "enlist" operator

Fixes #2767

core/modules/filters/enlist.js

@@ -0,0 +1,33 @@
+/*\
+title: $:/core/modules/filters/enlist.js
+type: application/javascript
+module-type: filteroperator
+
+Filter operator returning its operand parsed as a list
+
+\*/
+(function(){
+
+/*jslint node: true, browser: true */
+/*global $tw: false */
+"use strict";
+
+/*
+Export our filter function
+*/
+exports.enlist = function(source,operator,options) {
+	var list = $tw.utils.parseStringArray(operator.operand);
+	if(operator.prefix === "!") {
+		var results = [];
+		source(function(tiddler,title) {
+			if(list.indexOf(title) === -1) {
+				results.push(title);
+			}
+		});
+		return results;
+	} else {
+		return list;
+	}
+};
+
+})();

editions/tw5.com/tiddlers/enlist Operator (Examples).tid

@@ -0,0 +1,8 @@
+created: 20170221144328467
+modified: 20170221151620898
+tags: [[enlist Operator]] [[Operator Examples]]
+title: enlist Operator (Examples)
+type: text/vnd.tiddlywiki
+
+<<.operator-example 1 "[enlist[one two three]addsuffix[!]]">>
+<<.operator-example 2 "[enlist{$:/StoryList!!list}]">>

editions/tw5.com/tiddlers/enlist Operator.tid

@@ -0,0 +1,24 @@
+caption: enlist
+created: 20170221144241063
+modified: 20170221151340420
+op-input: ignored
+op-neg-input: a [[selection of titles|Title Selection]]
+op-neg-output: those input titles that are <<.em not>> listed in <<.place L>>
+op-output: the titles stored as a [[title list|Title List]] at <<.place L>>
+op-parameter: a [[title list|Title List]]
+op-parameter-name: L
+op-purpose: select titles from the operand interpreted as a [[title list|Title List]]
+tags: [[Filter Operators]] [[Field Operators]] [[Selection Constructors]] [[Negatable Operators]]
+title: enlist Operator
+type: text/vnd.tiddlywiki
+
+<<.tip " Literal filter operands cannot contain square brackets but you can work around the issue by using a variable:">>
+
+```
+<$set name="myList" value="first [[second with a space]] third">
+<$list filter="[enlist<myList>]">
+...
+```
+
+
+<<.operator-examples "enlist">>