Remove duplicate instance data saved in both root SCH_SCREEN and SCH_SHEET
objects that was causing them to be out of sync. All sheet instance data
is stored in the SCH_SHEET object itself and rebuilt on the fly so it is
always current.
Remove Get/SetPageNumber from SCH_SHEET_PATH object so it doesn't obfuscate
where the actual sheet page number information exists.
Fixes https://gitlab.com/kicad/code/kicad/-/issues/9782
Note: PGM_BASE::InitPgm() is creating a SETTINGS_MANAGER object, which
in turn tries to display a "migrate settings" dialog when no settings
are found, but obviously the dialog can't be displayed inside docker.
Needed to add an optional parameter to InitPgm() in order to allow
running in headless mode.
The groundwork has now been laid for per sheet instance data. Initially
this only supports sheet page numbers but could be expanded to include
other per sheet instance information.
ADDED: Support for user defined schematic page numbers.
Wayne Stambaugh
luz paz
Sylwester Kocjan
Roberto Fernandez Bautista
Jon Evans
Jeff Young