Combining cd and ls into j function.

If you analyze most users' command line history files, cd and ls usually top the list. For example my laptop's top 10 shell commands:

   1993 ls
   1334 cd
    445 g #alias for git
    418 sudo
    278 ssh
    276 git
    223 vim
    215 rm
    139 v #alias for vim
    126 mv

The default behavior for most users is to ls right after cd to the point that I have a function cl that basicly duplicates this behavior.