* Fixing that Core.Containers "Show on admin menu" functionality shouldn't depend on the Orchard.Lists feature
* Moving menu.list.png admin menu icon from Orchard.Lists to Core.Containers as menu.container.png
to fix that Containers should have a default admin menu icon
* Fixing conflict between lists and container admin navicon by applying the unused menu.list-definition.png to lists
* Code styling and removing duplicate code