and mentioned use of 2-space indentation in macro definitions in
the libpng style guide.

to eliminate bogus complaint about filter_type.

in png_set_gAMA_and_cHRM() where we supply the cHRM constants and
therefore we know they are OK.

also png_check_cHRM_fixed() which was apparently overlooked when it
was created.

Move redundant IHDR checking into new png_check_IHDR() in png.c
and report all errors found in the IHDR data.  Report problems
with width and height separately.

and revised libpng style to mention not using the TAB character.

to avoid compiler complaints about doubly declaring things "const".

about fixing the "#if def " bug

("#if def" should be "#ifdef")

to give Dennis Gustafsson credit for noticing the incorrect typecast
of "filler".

and always use png_calloc().  The macros were only there for testing,
since libpng-1.4.0beta48 and no problems have been reported.

from contrib/visupng and contrib/pngminim sources.

Always use local arrays, which has been the default behavior
for a long time.

instead of memset to zero in png_read_png().

They were only useful for obtaining compatibility for old applications
that used libpng-1.0.x versions prior to the implementation of "free_me".

except in pngconf.h where they can be used to request that
PNG_FEATURE_SUPPORTED not be defined.