#775 Passphrases in password policies

[David Latapie]

Upgrade the password policy generator to allow passphrases, like http://mymonero.com does for mnemonic seeds.

us-ascii words with spaces, pretty good entropy

Links:

• http://mymonero.com
• http://xkcd.com/936/
• https://moneroeconomy.com/faq/isnt-mnemonic-seed-and-inability-change-words-security-holes

The "no change ever" and "only 1626 words with unique four-first-letter set" restriction of mymonero (and electrum) can be scraped, resulting in even higher entropy.