nextpnr 0.4
- ECP5 switches to a split-slice view (separate LUT/FF bels) allowing higher utilisations
- several improvements to the gowin arch
- vendored pybind11 update to support Python 3.11
- iCE40, ECP5 and nexus bugfixes
- viaduct uarch for FABulous eFPGA fabrics
- initial PseudoCell API for region ports and other uses
- continued cleanups and refactoring (including new
ctx->idf(...)
API)