Don't clobber value file when load aliases in legacy symbol library cache
parser.
Use actual symbol library LIB_PART pointer rather than a flattened copy
of the symbol. This fixed a bug when displaying the parent field in the
message panel for derived symbols.
Simplify the flatten code by copying the parent and updating the lesser
information from the inherited symbol.
This change completely removes the LIB_ALIAS design pattern an replaces
it by allowing LIB_PART objects to inherit from other LIB_PART objects.
The initial implementation only allows for single inheritance and only
supports the mandatory fields in the derived part because that is all
that the current symbol library file format will support. Once the new
file format is implemented and saving to the old file format is deprecated,
more complex inheritance will be added. The LIB_ALIAS information saved
in the document files was move into the LIB_PART object. This change
impacts virtually every part of the schematic and symbol library editor
code so this commit message is woefully incomplete.
REMOVE: Removed the symbol aliases concept from the schematic and symbol
editors and the symbol viewer.
NEW: Replace the symbol alias concept with simple inheritance that allows
a library symbol to be derived from another library symbol.
The sort routine requires the value to be true with a is strictly lower
than b. But just inverting the '<' doesn't yield strictly lower, it
includes '>='. This causes items to jump in the list.
Copy/Paste should keep the original items' designation for all units and
conversion type. If it was specified in the original copy, we should
keep the same specification when pasting (but update for the current
frame)
