Make the files pane collapsible. This is the limit of my CSS ability.

git-svn-id: https://www.unprompted.com/svn/projects/tildefriends/trunk@3848 ed5197a5-7fde-0310-b194-c3ffbd925b24

core/client.js

@@ -113,6 +113,14 @@ function edit() {
 	});
 }
 
+function hideFiles() {
+	document.getElementById('filesPane').classList.add('collapsed');
+}
+
+function showFiles() {
+	document.getElementById('filesPane').classList.remove('collapsed');
+}
+
 function trace() {
 	fetch('/trace')
 		.then(function(response) {