[Pmt-exif] multiple textExif chunks?

[Glenn Randers-P. <gl...@ho...>]

I am considering eliminating the possibility of having multiple textExif
chunks in a PNG datastream.

It seemed useful at first, but it made the proposed eXIF chunk more complex,
and I no longer think it's that useful to be able to spread the Exif
information over multiple chunks.

Glenn