All: Remove the deprecated ui/core.js file

Also, fix checkboxradio visual tests.

Ref gh-2249

Author: mgol

Gruntfile.js

@@ -4,7 +4,6 @@ module.exports = function( grunt ) {
 
 // files
 const coreFiles = [
-	"core.js",
 	"widget.js",
 	"widgets/mouse.js",
 	"widgets/draggable.js",
@@ -167,7 +166,7 @@ grunt.initConfig( {
 				findNestedDependencies: true,
 				skipModuleInsertion: true,
 				exclude: [ "jquery" ],
-				include: expandFiles( [ "ui/**/*.js", "!ui/core.js", "!ui/i18n/*" ] ),
+				include: expandFiles( [ "ui/**/*.js", "!ui/i18n/*" ] ),
 				out: "dist/jquery-ui.js",
 				wrap: {
 					start: createBanner( uiFiles )

demos/slider/multiple-vertical.html

@@ -5,11 +5,6 @@
 	<meta name="viewport" content="width=device-width, initial-scale=1">
 	<title>jQuery UI Slider - Multiple sliders</title>
 	<link rel="stylesheet" href="../../themes/base/all.css">
-	<script src="../../external/jquery/jquery.js"></script>
-	<script src="../../ui/core.js"></script>
-	<script src="../../ui/widget.js"></script>
-	<script src="../../ui/mouse.js"></script>
-	<script src="../../ui/slider.js"></script>
 	<link rel="stylesheet" href="../demos.css">
 	<style>
 	#eq > span {

tests/visual/checkboxradio/checkboxradio.html

@@ -4,13 +4,8 @@
 	<meta charset="utf-8">
 	<title>jQuery UI - Checkboxes</title>
 	<link rel="stylesheet" href="../../../themes/base/all.css">
-	<script src="../../../external/jquery/jquery.js"></script>
-	<script src="../../../ui/core.js"></script>
-	<script src="../../../ui/widget.js"></script>
-	<script src="../../../ui/button.js"></script>
-	<script src="../../../ui/checkboxradio.js"></script>
-	<script>
-	$(function() {
+	<script src="../../../external/requirejs/require.js"></script>
+	<script src="../../../demos/bootstrap.js">
 		var checkboxes = $( "form input" ).checkboxradio();
 
 		$( ".controls input, .controls select" ).on( "change keyup", function() {
@@ -23,15 +18,14 @@
 			if ( option != "label" || value !== "" ) {
 				checkboxes.checkboxradio( "option", option, value );
 			}
-		});
+		} );
 		$( ".controls > button" ).on( "click", function() {
 			if ( this.id !== "create" ) {
 				checkboxes.checkboxradio( this.id );
 			} else {
 				checkboxes.checkboxradio();
 			}
-		});
-	});
+		} );
 	</script>
 	<style>
 	#format { margin-top: 2em; }