too break from "while" and issue a png_warning on over limit.

Removed unused "buffer_size" variable from png_decompress_chunk().

and updated the "last change" comments to 1.5.0

and undid the linewrapping that it required.
Revised comments in pngstruct.h and pnginfo.h and added pointers to
the libpng license.

from png.h

    in pngtest.c

and Makefile.in to be consistent with changes in libpng-1.4.0rc03