[png-mng-implement] libpng-1.5.0beta20 is available

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

libpng-1.5.0beta20 is available from
ftp://ftp.simplesystems.org/pub/png-group/src
and from
http://libpng.sf.net/

version 1.5.0beta20 [April 24, 2010]
  Added PNG_{READ,WRITE}_INT_FUNCTIONS_SUPPORTED.  This allows the functions
    to read and write ints to be disabled independently of PNG_USE_READ_MACROS,
    which allows libpng to be built with the functions even though the default
    is to use the macros - this allows applications to choose at app build
    time whether or not to use macros (previously impossible because the
    functions weren't in the default build.)
  Changed Windows calling convention back to __cdecl for API functions.
    For Windows/x86 platforms only:
      __stdcall is no longer needed for Visual Basic, so libpng-1.5.0 uses
      __cdecl throughout (both API functions and callbacks) on Windows/x86
      platforms.
  Replaced visualc6 and visualc71 projects with new vstudio project
  Relaxed the overly-restrictive permissions of some files.

Glenn