Remove argument parsing from cut implementation.
Refactor tests for argument parsing.
Refactor tests to eliminate redundancy.
Refactor tests to eliminate external dependency.
Fix default values for arguments -f and -d
Copy while file when no field is selected.
Some notes about functionality.
Clean up.
Add check for write error.
Read non flag arguments as file names.
Open files for reading.
Move comments into README.
Hooking things up in main.