No lock/unlock of in-map details

The lock/unlock "feature" for in-map details continually causes trouble.

In the past serious efforts were taken already, but w/o satisfying result (#266 (closed)).

Subject of this ticket:

Both, node-level actions and content-level actions are immediately available. No lock/unlock anymore.
Node-level actions comprise: a) select, b) move, c) open context menu, d) create assoc, e) "opening" (double clicking), ...
Content-level actions comprise: a) reveal child topic, b) inline edit, c) text selection, d) clicking links, e) scrolling, f) interacting with embedded content, e.g. audio/video players, ...
A node's details view is placed towards bottom (instead of center-point aligned as it is now).
In particular no edge geometry changes along with show/hide details.