Changes:
- Added support for formatting day of the month without leading zero ("sday").
- Changed date format in place profile (landmark info) and in the top status bar
  according to bug reporter's request.

Technical details:
Actually implementation of strftime() in Linux and Windows supports stripping the
leading zero (with "%-d" and "%#d" respectively).
But that's not supported in MacOSX, so I had to reimplement it.

Reviewed by Sergey Litovchuk at https://codereview.productengine.com/secondlife/r/842/