png_memset(), png_memcpy(), and png_memcmp() macros.

except in pngtest.c and example.c where these macros are not visible.

patch; they are needed by png_set_IHDR() for both read and write.  Fix
some ifdefs that caused the contrib/pngminim/ applications to not compile.

a consistent style for (sizeof type) and (sizeof (array))

    iCCP profile over writing the sRGB chunk, controlled by the
    PNG_sRGB_PROFILE_CHECKS option.

load iCCP

functions [rw]util.c.  A new shared keyword check routine was also added
and the 'zbuf' is no longer allocated on progressive read.  It is now
possible to call png_inflate() incrementally.

If the call to deflateInit2() is wrong a png_warning will be issued
(in fact this is harmless, but the PNG data produced may be sub-optimal).

read code now claims and releases png_ptr->zstream, like the write code.
The bug whereby the progressive reader failed to release the zstream
is now fixed, all initialization is delayed, and the code checks for
changed parameters on deflate rather than always calling
deflatedEnd/deflateInit.

all potentially valid ICC profiles and reject obviously invalid ones.
It now uses png_error() to do so rather than casually writing a PNG
without the necessary color data.

Added new "png_structrp" typedef. Because of the
way libpng works both png_info and png_struct are always accessed via a
single pointer.  This means adding C99 'restrict' to the pointer gives
the compiler some opportunity to optimize the code.  This change allows that.

in compressed text writing

introduced in 1.5.6bet01.

to conditions where types that are 32 bits in the GCC 32-bit
world (uLong and png_size_t) become 64 bits in the 64-bit
world.  This produces potential truncation errors which the
compiler correctly flags.

Fixed some compiliation problems with scaling options.

    wrong (high by one) 25% of the time. Dividing by 257 with rounding is
    wrong in 128 out of 65536 cases. Getting the right answer all the time
    without division is easy.

 (libpng-manual.txt still to be updated, see png.h for documentation.)

This was because the attempt to reset the zlib stream in png_write_IDAT
happened after the first IDAT chunk had been deflated - much too late.
In this change internal functions are added to claim/release the z_stream
and, hopefully, make the code more robust.  Also deflateEnd checking is
added - previously libpng would ignore an error at the end of the stream.

optimization configureable.

 This change adds internal APIs to allow png_warning messages to have parameters
 without requiring the host OS to implelment snprintf.  As a side effect the
 dependency of the RFC1132 code on stdio is removed and PNG_NO_WARNINGS does
 actually work now.