Wrap wide chars in a span/class

Part of #439

src/xterm.js

@@ -1182,6 +1182,9 @@ Terminal.prototype.refresh = function(start, end, queue) {
         }
       }
 
+      if (ch_width === 2) {
+        out += '<span class="xterm-wide-char">';
+      }
       switch (ch) {
         case '&':
           out += '&amp;';
@@ -1200,6 +1203,9 @@ Terminal.prototype.refresh = function(start, end, queue) {
           }
           break;
       }
+      if (ch_width === 2) {
+        out += '</span>';
+      }
 
       attr = data;
     }