[trunk] Handle cmap where direct use is specified (issue235_cmapsubbox.jp2)

[trunk] Handle cmap where direct use is specified (issue235_cmapsubbox.jp2)
I doubt the old code ever work. The new code copy the old codestream bytes into the new components (instead of copying the pointer).
Technically the issue235.jp2 file should be handled since I.5.3.5 specifies that:
...
If the JP2 Header box does not contain a Component Mapping box, the components shall be mapped directly to channels,
such that component i is mapped to channel i.
...
Update issue 235