Merged script files, added README.md instructions.

[145818]

This change make the script run with flags and only one script file is needed.

Activate firewall: firewall -u

Take down firewall: fireall -d

Reload firewall: firewall -r

This really depends on preference so I can see and understand if you don't accept it. If so, I'll just keep this version alive over at https://codeberg.org/tilt/fw , thanks either way for making this script to begin with.