Replace Make Persistent with something better

These feature was the only way to have more than one tool in use at the same time in one side bar. As long as you never clicked on some tab to switch some tool was all fine. But when, you ended quickly in a situation where your desired layout was damaged.

With this patch you can group tools in tab bars, called sections, and nicely switch between them without to break your layout.

Pls see commit messages for more details.

HINT: While working on this has Ahmad Samir made changes on the Sidebar too. The rebase of my local branch to the new master was not so easy and so are some improvements (unintended) removed. Sorry.