The simulator has advanced considerably, and it is seeing lots of active
development, so make it a required part of KiCad. Additionally, the
build without the simulator has actually been broken for a while, so no
one clearly is building without ngspice right now.
Also includes fixes for instance data and resolving of textvar
references.
Also includes virtual d'tors for IBIS parser to get rid of all the
compile warnings on CLang.
Fixes https://gitlab.com/kicad/code/kicad/issues/12357
Follow-up after the KIBIS and KIBIS GUI merge requests.
- Move KIBIS from Pcbnew to Eeschema space,
- Make KIBIS obtain the Ku/Kd coefficients via the `SPICE_SIMULATOR` class instead of calling the `ngspice` executable via `system()`,
- Allow to toggle between differential and single-ended model in the GUI,
- Various GUI fixes and improvements.