Add remove from merge list to unitlist right click option

[chrishalcrow]

(if we agree on this, I'll add it to panel)

Two changes:

1. When you select something, the unit list's scrollbar position now updates to show the first unit in the unit you've selected. This means if you click on a unit on ProbeView you immediately see it in the UnitView. This tiny change has made life way more fun in the gui

2. you can remove selected units from a merge. See below.

Note: we check that you can do this action.

2026-01-30.12-43-23.mp4