Update to 1.2.37:

version 1.2.37beta01 [May 14, 2009]
  Fixed inconsistency in pngrutil.c, introduced in libpng-1.2.36.  The
    memset() was using "png_ptr->rowbytes" instead of "row_bytes", which
    the corresponding png_malloc() uses (Joe Drew).
  Clarified usage of sig_bit versus sig_bit_p in example.c (Vincent Torri)
  Updated some of the makefiles in the scripts directory (merged with
    those in libpng-1.4.0beta57).

version 1.2.37beta02 [May 19, 2009]
  Fixed typo in libpng documentation (FILTER_AVE should be FILTER_AVG)
  Relocated misplaced #endif in pngwrite.c, sCAL chunk handler.
  Conditionally compile png_read_finish_row() which is not used by
    progressive readers.
  Added contrib/pngminim/preader to demonstrate building minimal progressive
    decoder, based on contrib/gregbook with embedded libpng and zlib.

version 1.2.37beta03 [May 20, 2009]
  In contrib/pngminim/*, renamed "makefile.std" to "makefile", since there
    is only one makefile in those directories, and revised the README files
    accordingly.
  Reformated sources in libpng style (3-space indentation, comment format)

version 1.2.37rc01 [May 27, 2009]
  No changes.

versions 1.2.37 and 1.0.45 [June 4, 2009]
  Reformatted several remaining "else statement;" and "if () statment;" into
    two lines.
  Added "#define PNG_NO_WRITE_SWAP" to contrib/pngminim/encoder/pngusr.h
    and "define PNG_NO_READ_SWAP" to decoder/pngusr.h and preader/pngusr.h
  Added sections about the git repository and our coding style to the
    documentation (merged from libpng-1.4.0beta62)
  Added a section about using png_get_io_ptr() in configure scripts to detect
    the presence of libpng.


(wiz)