Add some new features to the cd command:
* `cd`: go to %HOME% or %USERPROFILE%
* `cd -`: go to previous directory
* `h`: show 10 lines of history
* `cd [0-9]`: go to the history lines passed in parameter
* `p`: pop the last line in the history, and go there (sort of undo cd)
Also, no need to pass the `/d` parameter anymore, cd will change the
drive automatically.