yosys-netlist-json: Make structures fully compliant
yosys-netlist-json: Make structures fully compliant

The parser should now be equally as liberal as the Yosys parser. More
tests will be added in later commits.

azonenberg/openfpga,rqou/openfpga,azonenberg/openfpga,rqou/openfpga,azonenberg/openfpga,rqou/openfpga,rqou/openfpga,rqou/openfpga,azonenberg/openfpga,azonenberg/openfpga