Long list of edit updates

Better option/arg parsing, more options functional (-e, -l, -r, -i, file), stores comments and newlines (in an inefficient way, but functionality first and then optimize), handles non-existent users and underprivileged access. I default the user to their euid, and do not fully delete the user's crontab (I nullify it, but the program behaves as if it is deleted).