Feature - ability to sort panels

[patrickkusebauch]

Right now panels are render on the order they are added into the Bar class. It would be nice to have the option to sort the panel before rendering (maybe based on ID), so that you don't have to visually scan all the panels to find the one you are looking for.

If you find this to be a good idea, I am willing to write a PR for it.

[janbarasek]

For sorting, there could be a callback function where a particular implementation registers its own sorting logic that gets an array of panels and returns it in sorted order. The callback should return an array of panel name keys (array<int, string>) so the new unknown panel cannot be added or removed (security prevention).