#22 #23 "set" now correctly expands variables, almost can run my batch
file.

The "set" command now correctly expands all variables in a command and
reruns that command. However, if a command is already running, this
needs to be changed to pass the text unchanged to the running command.

I can almost run my target batch file but it fails because the batch
file invokes the "%CD%" variable (current directory). With my current
design, I don't like the ways I can get the current direcotry. I will
look into adding support for symbolic variables like $CD.

For now, though, I will just get it working however I can.