Edit style: add Ctrl-S hotkey to save the style

edit.html

@@ -152,7 +152,7 @@
 				<div><label for="enabled" id="enabled-label"></label><input type="checkbox" id="enabled"></div>
 			</section>
 			<button id="to-mozilla"></button><img id="to-mozilla-help" src="help.png"><br><br>
-			<button id="save-button"></button>
+			<button id="save-button" title="Ctrl-S"></button>
 			<a href="manage.html"><button id="cancel-button"></button></a>
 			<div id="options">
 				<h2 id="options-heading"></h2>

edit.js

@@ -15,6 +15,7 @@ sectionTemplate.innerHTML = '<label>' + t('sectionCode') + '</label><textarea cl
 var editors = [] // array of all CodeMirror instances
 // replace given textarea with the CodeMirror editor
 function setupCodeMirror(textarea) {
+	CodeMirror.commands.save = function(cm) { save() }
 	var cm = CodeMirror.fromTextArea(textarea, {
 		mode: 'css',
 		lineNumbers: true,