Revision history for String::Defer.
3       2012-01-03
    - 5.15 changes the behaviour of LVALUE substr.
2       2011-11-01
    - Skip the ~~ test on 5.10.0.
    - Document the cases where perl stringifies too soon.
1       2011-10-24
    Initial release.
        - Deferring of scalar or code refs.
        - Deferred concatenation.
        - Deferred joins.