v0.5.1

• remove deprecated getLocalizedStrftime function
• make %C pad the century with spaces, like C
• list all supported specifiers in the readme, it's no longer fair to say "look at man 3 strftime"
• use fixed dates in the readme instead of "now", so people can execute the examples and see the same results
  Thanks to John Zwinck
• fix %z for timezones greater than GMT
• support any Date-like objects instead of checking for actual instances of Date