    - test tzoffset
    - make more tests (see Devel::Cover)
    - clean up xs
    - allow cdate() to print as different formats
    - Document format flags that don't work everywhere (see comments in *.t files)
    - move strptime() from XS to pure perl. See DateTime::Format::Strptime for a complicated example 
        Possible logic: parse date into tm struct, get epoch and then convert back to tm struct get a properly normalized form
    - Every "return 0" in the strptime case statement in Piece.xs needs to be preceded by a useful error statement
