Also netware.txt

(ported from the "master" branch)

(evidently the same change made in libpng-1.0beta54 was lost).

and removed the deprecated png_check_sig() function.

    so that only PNG_EXPORT functions are exported.

Only #define PNG_DEPSTRUCT, etc. in pngconf.h if not already defined.

  Updated projects/visualc6 and visualc71 with "/d PNG_CONFIGURE_LIBPNG".
    They should work but still need to be updated to remove
    references to pnggccrd.c or pngvcrd.c and ASM building.
  Added README.txt to the beos, cbuilder5, netware, and xcode projects warning
    that they need to be updated, to remove references to pnggccrd.c and
    pngvcrd.c and to depend on pngpriv.h

to prevent warnings about direct access to png structs by libpng functions
while building libpng.  They need to be tested, especially
those using compilers other than gcc.

  Added PNG_DEPSTRUCT, PNG_DEPRECATED, PNG_USE_RESULT, PNG_NORETURN, and
    PNG_ALLOCATED macros to detect deprecated direct access to the
    png_struct or info_struct members and other deprecated usage in
    applications (John Bowler).
  Added -DPNG_CONFIGURE_LIBPNG to the makefile CFLAGS, to prevent warnings
    about direct access to png structs by libpng functions while building
    libpng.
  Removed three direct references to read_info_ptr members in pngtest.c
    that were detected by the new PNG_DEPSTRUCT macro.
  Moved the png_debug macro definitions and the png_read_destroy(),
    png_write_destroy() and png_far_to_near() prototypes from png.h
    to pngpriv.h (John Bowler)
  Moved the synopsis lines for png_read_destroy(), png_write_destroy()
    png_debug(), png_debug1(), and png_debug2() from libpng.3 to libpngpf.3.

instead of between 1.2.41 and 1.4.0 in documentation.