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.
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.
Mike Williams
Wayne Stambaugh
Jeff Young