Add options.onPosition and deprecate top and left (#385)

src/jquery.uls.core.js

@@ -119,6 +119,11 @@
 				top = this.top,
 				left = this.left;
 
+			if ( this.options.onPosition ) {
+				return this.options.onPosition.call( this );
+			}
+
+			// Default implementation (middle of the screen under the trigger)
 			if ( top === undefined ) {
 				pos = $.extend( {}, this.$element.offset(), {
 					height: this.$element[ 0 ].offsetHeight
@@ -380,9 +385,9 @@
 	};
 
 	$.fn.uls.defaults = {
-		// CSS top position for the dialog
+		// DEPRECATED: CSS top position for the dialog
 		top: undefined,
-		// CSS left position for the dialog
+		// DEPRECATED: CSS left position for the dialog
 		left: undefined,
 		// Callback function when user selects a language
 		onSelect: undefined,
@@ -392,6 +397,8 @@
 		onReady: undefined,
 		// Callback function when ULS dialog is shown
 		onVisible: undefined,
+		// Callback function when ULS dialog is ready to be shown
+		onPosition: undefined,
 		// Languages to be used for ULS, default is all languages
 		languages: $.uls.data.getAutonyms(),
 		// The options are wide (4 columns), medium (2 columns), and narrow (1 column).