Major rewrite of the script

[Gobidev]

I was playing a lot of CTF lately and was looking for a cli program that could automatically generate the reverse shells. This project was almost what I was looking for, although I wanted a way to output nothing but the reverse shell to be able to pipe it directly to my clipboard (i.e. ./script.py [...] | xclip). I therefore added the -s argument to do exactly that. While going through the code I noticed a few things that I thought could be improved so I ended up rewriting most of the script. I also had to convert the line endings from the dos to the unix format for the shebang line to work, thats why every line got modified in some way. I understand if you don't want to pull this fork since the code is very different to your original version but I tried to make as little changes as possible to how the output is displayed. The main difference noticable is that listing all shells has a header for every shell now since I outsourced the shell generation to a separate function.