Don't assume all identical references should have the same value.
Filter by checking that only symbol units having the same reference
also have the same library identifier before updating the value and
footprint fields.
Fixes https://gitlab.com/kicad/code/kicad/-/issues/8313
Adds ability to start new commit to eeschema, allowing all
AddItemsToUndoList to always append without foreknowledge. Keeps newly
split wires on the tool until placed
Fixes https://gitlab.com/kicad/code/kicad/issues/7512
1) Generalize SCH_ITEM owners (SCH_COMPONENT, SCH_SHEET, and now
SCH_GLOBALLABEL)
2) Generalize hypertext items
3) Use SCH_FIELD autoplace infrastructure for placing intersheet
references
4) Use textVar infrastructure for buildin intersheet references.
As an important side-effect this also fixes the undo issues with
intersheet refs.
This moves EESchema DLIST structures to rtree. These changes are more
fundamental than the pcbnew changes from 9163ac543888c01d11d1877d7c1
and 961b22d60 as eeschema operations were more dependent on passing
drawing list references around with SCH_ITEM* objects.