Revert "Popout inbox"

This reverts commit 31e7d285e3.

This seemed like a nice feature, but the popup bubble isn't very
conducive to nontrivial user inputs, e.g. file inputs.

Fixes #211

js/panel_controller.js

@@ -133,12 +133,6 @@
         }
     };
 
-    window.popoutInbox = function() {
-        chrome.browserAction.setPopup({popup: ''});
-        extension.browserAction(window.openInbox);
-        window.openInbox();
-    };
-
     // make sure windows are cleaned up on close
     extension.windows.onClosed(function (windowId) {
         if (windowMap.windowId[windowId]) {