- the default tifflib warning handler was crashing on Win32

    - the default tifflib warning handler was crashing on Win32
          under ActivePerl, when an unrecognized tag was read from the
          file.  For now we'll just drop the warnings in the bit bucket.
          (Ticket #1513)
        - the code to read multiple tiffs didn't handle files with more
          than five images correctly, causing a memory overrun.