Open sidebar on mouseover if not fixed.

[soerendomroes]

Fixes #213

By checking the panel id instead of contacting the renderoptions registry, this works very well.

However, this will open the sidebar onmouseover even though it is not pinned to be more reactive.

Maybe it would be a better idea to cache the pinned status rather than looking in the registry.

[Eddykasp]

I think this mainly needs user approval, which we can discuss in a meeting, but I think it's a good improvement.

[NiklasRentzCAU]

Our feedback from the discussion was that this should include the following changes:

• most recently opened pane should be reopened
• lock should toggle between always use click or always use hover