Add option to disable symbols in password

[bramstoeller]

In the original program "It's possible to generate passwords with no symbols using --no-symbols or -n", could you add this to the Windows implementation? Or would you mind if I added it? I'm not C# programmer, but I could give it a try. I think it should be a checkbox in Genpass.cs and then we should add an if-statement in pwgen.cs (line 115).

[mbos]

Good suggestion, will add it to the next release.