Previously, bus elements that were not instantiated as individual nets
could not connect to each other. This caused issues for complex
schematics where busses needed to connect to other busses with elements
that resolved to the same net names. Functionally, this means mixing
bus elements, which we will replace with first-class elements in version
8 but currently can only be accomplished either by using bus aliases and
this patch or by individually instantiating each bus element as a
local label
Fixes https://gitlab.com/kicad/code/kicad/issues/14300
(cherry picked from commit 16b4ec3c7e)
Also fixes some plot bugs with arcs.
Also moves polygonization of arcs (when required) in plotting code
from 5 degrees to calculated based on ARC_HIGH_DEF.
Fixes https://gitlab.com/kicad/code/kicad/issues/5017
Set up a new lineage for SCH_ITEMS to get back to the SCHEMATIC
they live on: Items will all be parented to the SCH_SCREEN that
they are added to, and each SCH_SCREEN will point back to the
SCHEMATIC that it is part of. Note that this hierarchy is not
the same as the actual schematic hierarchy, which continues to
be managed through SCH_SHEETs and SCH_SHEET_PATHS.
Bus upgrades: core new connectivity code
Bus upgrades: eeschema integration and modifications
Bus upgrades: eeschema dialogs
Bus upgrades: netlist export
Bus upgrades: file format changes