dont display:none hidden shells

Following suggestions in #109

This actually fixes the spliced video transition lag!
Except for the first playthrough...

Author: jbenet

less/acorn-player.less

@@ -63,6 +63,14 @@
   display: none !important;
 }
 
+.shell-media-view .hidden {
+  display: inherit !important;
+  margin-top: 10000px;
+  margin-left: 10000px;
+  z-index: -1000;
+  opacity: 0.01;
+}
+
 .transparent {
   .opacity(0);
 }