v2.8.0
https://www.bitaddress.org/bitaddress.org-v2.8.0-SHA1-87dcf19f02ee9fb9dd3a8c787bcf52eef944aa82.html
 - more entropy from browser fingerprinting for PRNG seed
 - user can add entropy through URL hash tag
 - seed mouse movement as 16-bit number
 - whole seed pool initially filled by window.crypto.getRandomValues
 - added textbox as an alternative input source for entropy
 - address will not generate without a minimum amount of human added entropy
   from mouse or keyboard
 - discard mouse movements less than 40ms apart
 - visualize points of entropy collection from the mouse