Update Time-Piece to CPAN version 1.20

Update Time-Piece to CPAN version 1.20

  [DELTA]

  1.20
    - Fix for alloca broke Solaris
    - Fixed documentation buggette about strptime
    - Added ->pretty() method for Time::Seconds objects
        - Add %s support to strptime

  1.19
    - Fix for alloca broke FreeBSD

  1.18
    - Fix for alloca on IRIX

  1.17
    - Force all to use internal strptime then everyone gets %z even OSX
      users.
    - Finally figured out the timezone test failures on Win32 and fixed
      them.

  1.16
        - Implement %z for the internal implementation of strptime().
          Unfortunately this doesn't get picked up everywhere, so there are no
          tests for it (yet - patches welcome).
        - Fix for major bug in add_months() using negative months which were
          multiples of 12. Also affected add_years() with negative years.
        - Fix for object creation bug in get_epochs which called new from object
          but that wasn't supported in the new() code.
        - Added docs about the weakness of using epoch seconds internally and
          suggested alternatives.
        - Removed useless "use UNIVERSAL qw(isa)" line.
        - Fix for installing over core perl version.