Random String

Hi Snipe - I know, you dont want extra staff that makes banbuilder too complicated. But I only added support for 3rd param longer than 1 char.
In the prev contribution, you could pass '@' to replace 'fuck' with @@@@ instead of ****.
Here I add the ability to pass '@#%$°!', to generate random strings with those chars, like '#@#°' or '%x°#'.
I hope that you will accept this.
Bye!