minor change from the previous (unreleased) ABI/API to hide the exact value
used for Macs - it's not a good idea to embed this in the ABI!

some currently dead code in pngrtran.c that will be enabled in libpng-1.6

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

 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.

handling. Internal changes only except for a new option to avoid compiling
in the png_build_grayscale_palette API (which is not used at all internally.)
The main change is to move the transform tests (READ_TRANSFORMS,
WRITE_TRANSFORMS) up one level to the caller of the APIs.

(it was looking for the flag in png_ptr->transformations instead of in
png_ptr->flags).

Certain optional gcc warning flags resulted in warnings in libpng code.
With these changes only -Wconversion and -Wcast-qual cannot be turned on.
Changes are trivial rearrangements of code.  -Wconversion is not possible
for pngrutil.c (because of the widespread use of += et al on variables
smaller than (int) or (unsigned int)) and -Wcast-qual is not possible
with pngwio.c and pngwutil.c because the 'write' callback and zlib
compression both fail to declare their input buffers with 'const'.

that CCP writes to standard output by default (Martin Banky).

Studio 2010 (John Bowler).

depending on PNG_16BIT_SUPPORTED

and shortening problems on assignment but also a few difficult to optimize
(for GCC) loops (John Bowler).

Also added scripts/chkfmt to validate the format of all the files that can
reasonably be validated (it is suggested to run "make distclean" before
checking, because some machine generated files have long lines.)
Reformatted the CHANGES file to be more consistent throughout.

literal pointers declare them (John Bowler).
Many APIs did not change their arguments but were not declared using
PNG_CONST.  This change corrects this.  In a few cases APIs that return
constant string literal pointers have also been changed to declare this.
Unlike the argument change this may require app changes; however the
results could never be written to (the app would crash on some platforms
where strings are not writable), so this seems advisable.