Adjusting borders around editable regions

[ellatrix]

At the moment it's not that nice that there are borders around all editable regions when you're editing. In the future this will be even worse when there's a border around the area where you can edit tags, categories and the date. One solution is to keep the borders, but let them disappear once you select one of the areas. To see them again, you can click outside the area and all of them will reappear. The downside here is that on mobile devices for example it might not be easy to find this areas.

[ellatrix]

Duplicate of #293.