This changes the file format. All previous copper layers that had a user
defined name are forced back to the canonical name and the user defined
name is stored as an optional quoted string in the layer definition and
only used for UI and plotting purposes. All copper object layer names
are now the canonical name for internal file use.
ADDED: Nine new user definable non-copper layers that can be optionally
added to the board layer stack.
CHANGED: All board layers can now be renamed by the user.
CHANGED: User defined layer names can now contain space characters.
Fixes https://gitlab.com/kicad/code/kicad/issues/1969
When importing settings from a board with more copper layers and applying it
to a board with less copper layers, if the user has ticked the checkbox
"Layer settings", then KiCad will delete the inner copper layers. Only
when the user clicks OK does it then warn that it found deleted items on inner
layers. The message is too generic and comes after the layers have already
been deleted.
This Merge Request tries to address this by warning them early. The changes are:
1 - Added code to check if user is trying to import settings from a
board with less copper layers than the current loaded board. This
results in KiCad deleting inner copper layers. Now it presents a
warning dialog that explains the current settings will result in deleted
inner layers, and lets the user stop the import process before making any changes.
2 - Made "Import Settings" dialog disable "Import Settings" button
until at least one import option checkbox is checked.
3 - Made "Select All" button on "Import Settings" dialog toggle
between "Select All" and "Deselect All" on each click.
Items 2&3 were added to improve the overall import settings usability
experience.
Fixes issue https://gitlab.com/kicad/code/kicad/-/issues/4904