Update MinGW requirements, etc.
Update MinGW requirements, etc.

The old readline library was causing problem. I updated the mingw.txt
file to use the gnuwin32 version of readline (5.0-1) which works. I
also mentioned that I plan to rewrite the directions using a newer
version of MinGW.

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