Handle unique/strange password requirements

[shibacomputer]

As per #76, some password policies are wacky. Encryptr should be able to generate passwords that work with all of them.

Off the top of my head, we will need to handle:

• Upper/lowercase characters
• Numeric characters
• Option to remove non alpha-numeric characters
• Length
• Pronouncability

Comments on this are welcome.

[edent]

Some policies prevent consecutive characters from matching (Look) or from sequences (abc, 12345, etc).

It's probably impractical to add those as options - but a big "Pick New Password" button would hopefully be enough to choose another random string.

[edent]

Characters outside the ASCII range should also be an option.

E.g. A password of 🎉🎸🍪🐹🐟🍈 or Bill莎士比亚