Rename racket/cmdline to racket/command-line.

[gus-massa]

• Rename racket/cmdline to racket/command-line.

Extracted from the old racket2 wiki. #33

[gus-massa]

I think its better to keep the old name racket/cmdline to not break working programs, and make a new racket2/command-line with a better name for new programs.

This is related to the interoperability between racket1 and racket2 #13

I'd also like to change the order of one of the functions make-custom-hash-types and make-custom-set-types. #29 Perhaps keep in the old order in racket/something and use the new more consistent order in racket2/something.