Add new 'minlength' operator

Fixes #1493

core/modules/filters/minlength.js

@@ -0,0 +1,29 @@
+/*\
+title: $:/core/modules/filters/minlength.js
+type: application/javascript
+module-type: filteroperator
+
+Filter operator for filtering out titles that don't meet the minimum length in the operand
+
+\*/
+(function(){
+
+/*jslint node: true, browser: true */
+/*global $tw: false */
+"use strict";
+
+/*
+Export our filter function
+*/
+exports.minlength = function(source,operator,options) {
+	var results = [],
+		minLength = parseInt(operator.operand || "",10) || 0;
+	source(function(tiddler,title) {
+		if(title.length >= minLength) {
+			results.push(title);
+		}
+	});
+	return results;
+};
+
+})();

editions/tw5.com/tiddlers/filters/examples/minlength.tid

@@ -0,0 +1,11 @@
+created: 20161011074235805
+modified: 20161011074235805
+tags: [[Operator Examples]] [[minlength Operator]]
+title: minlength Operator (Examples)
+type: text/vnd.tiddlywiki
+
+<<.using-days-of-week>>
+
+<<.operator-example 1 "[list[Days of the Week]minlength[7]]">>
+<<.operator-example 2 "[list[Days of the Week]minlength[1]]">>
+

editions/tw5.com/tiddlers/filters/minlength.tid

@@ -0,0 +1,14 @@
+caption: minlength
+created: 20161011074235805
+modified: 20161011074235805
+op-input: a list of items
+op-output: those items at least as long as the specified minimum length
+op-parameter: the minimum length for items
+op-parameter-name: minlength
+op-purpose: filter items shorter than the specified minimum length
+from-version: 5.1.14
+tags: [[Filter Operators]]
+title: minlength Operator
+type: text/vnd.tiddlywiki
+
+<<.operator-examples "minlength">>