Managing CD in a pipe.

[pabloabap]

Thanks for share the exercise, very helpful!
Added a quick fix when cd is used in a pipe. Bellow some case of the program before the fix:

1. ___ Microshell ___
   input > ./microshell cd . "|" /bin/wc
   output > nothing. Seems /bin/wc is waiting for input in the pipe.
   ___ Bash ___
   input > cd . | /bin/wc
   output > 0 0 0

2. ___ Microshell ___
   input > ./microshell /bin/ls "|" cd . "|" /bin/wc
   output > 3 3 29 Seems /bin/wc count the output of /bin/ls
   ___ Bash ___
   input > /bin/ls | cd . | /bin/wc
   output > 0 0 0