Reuse SecureRandom, rather than re-seeding every time (which is bad for
performance). Default re-seeding to occur hourly, but make it
configurable via BCryptReseedFrequency configuration variable.
Removed a debugging variable.
Whitespace fix.
Merge pull request #1245 from jamiejackson/6.0

Improving Password Hashing Performance Under Load
@jamiejackson Thanks, I appreciate the detailed investigation!