Yosys 0.28

Yosys 0.27 .. Yosys 0.28

• Verilog

  • Out of bounds checking for struct/union members.

• Verific support

  • Fix enum_values support and signed attribute values.

• ECP5 support

  • Added "synth_ecp5 -iopad"

• MachXO2 support

  • Added "synth_machxo2 -ccu2"