Media: Fix image cropping on touch screen devices.

* In initCrop, handle touch events in addition to mouse events.
* In imageSelect jQuery plugin, accept event.which of 0 as provided by touch events.

Props yahil, alexgso, joemcgill.
Fixes #41242.

Built from https://develop.svn.wordpress.org/trunk@42818


git-svn-id: http://core.svn.wordpress.org/trunk@42648 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-admin/js/image-edit.js

@@ -653,7 +653,7 @@
 				 *
 				 * @returns {void}
 				 */
-				parent.children().mousedown(function(e){
+				parent.children().on( 'mousedown, touchstart', function(e){
 					var ratio = false, sel, defRatio;
 
 					if ( e.shiftKey ) {