Fix the modpath edge and vpi_put_delay() code
Fix the modpath edge and vpi_put_delay() code

The code to get the correct modpath delay for a given edge had the X and Z
entries swapped.

When putting a delay from the VPI the 2 delay to twelve delay mapping was
incorrect and the to/from X delays were also not being calculated correctly.

CastMi/iverilog,CastMi/iverilog,themperek/iverilog,themperek/iverilog,CastMi/iverilog,themperek/iverilog