added minimize button to chat modal

templates/chat.tpl

@@ -6,6 +6,7 @@
 			<div class="modal-header">
 				<button id="chat-close-btn" type="button" class="close" data-dismiss="modal" aria-label="Close"><span aria-hidden="true">&times;</span></button>
 				<button type="button" class="close hidden-xs hidden-sm" data-action="maximize"><span aria-hidden="true"><i class="fa fa-expand"></i></span><span class="sr-only">[[modules:chat.maximize]]</span></button>
+				<button type="button" class="close hidden-xs hidden-sm" data-action="minimize"><span aria-hidden="true"><i class="fa fa-minus"></i></span><span class="sr-only">[[modules:chat.minimize]]</span></button>
 				<button class="close" component="chat/controlsToggle"><i class="fa fa-gear"></i></button>
 
 				<h4><!-- IF roomName -->{roomName}<!-- ELSE -->{usernames}<!-- ENDIF roomName --></h4>