To implement unusual IOs that have a dynamically changing configuration
it is convenient to store the switching method in the additional chip
data.
Signed-off-by: YRabbit <rabbit@yrabbit.cyou>
- minor fixes for pinout saving;
- CST parser taken from generic-based apicula;
- $nextpnr IOB detachment is copied here because it is necessary to copy
attributes from deleted bels.
Signed-off-by: YRabbit <rabbit@yrabbit.cyou>