:::::::README Lab 1::::::::

Team:
Ryan Schultz 403923115
Peter (Sangyeop) Lee 003950078

Implementing a simpler version of UNIX shell.


Lab 1a:
Seems to be able to handle every known case

Issues:
haven't found any issues.

Lab 1b:
Issues:
If a certain series of commands is put into a .sh file and executed using
./timetrash the correct output is shown, but if a test is performed in the style of test-p-ok.sh
,some errors will be generated.

Lab 1c:
Issues:
there doesn't seem to be known issues at the moment. 
but when I try to run certain cases in the way test-p-ok.sh is done under time-travel mode, certain
independent commands, (ex: echo line) would not execute from time to time. but when i execute such commands 
in a shell script on bash, it will always be executed. 

Implementation Summary:
First of all, we have revamped our read-command.c code.
We have implemented another function called execute_command_t for time_travel mode. 
We modified read-command.c, such that every command will have array of pointers to commands that it depends on and to
commands that depend on current command. Then, in execute_comand_t, we used two queues, one for independent commands, and one for dependent commands.
queue was implemented using linked-list. Then, first while loop will execute all the independent commands first in parallel, and the second
while loop will execute the dependent commands. Inside the second while loop, for every iteration, it waits for all the commands 
that current dependent command depends on to finish before executing the current dependent command itself.