new icestorm/arachne/yosys fpga toolchain port for cad/

[Ash Gokhale]

I've ported  Cliford Wolf's/ Cotton Seed's amazing
icestorm/yosys/arachne-pnr  open source toolchain for the lattice fpga
bitstream generation, verilog translation, place and route engine  and
supporting synthesis tools.

It works for me (tm) to the point of actually programming hadware. I would
appreciate feedback or inclusion into the ports tree.
https://github.com/agokhale/freebsd-port-arachne-pnr
https://github.com/agokhale/freebsd-port-yosys
https://github.com/agokhale/freebsd-port-icestorm