Log Message:
Changes 1.2.7:
* Removed unused pngasmrd.h file.
* Removed references to uu.net for archived files.  Added references to
    PNG Spec (second edition) and the PNG ISO/IEC Standard.
* Added "test-dd" target in 15 makefiles, to run pngtest in DESTDIR.
* Fixed bug with "optimized window size" in the IDAT datastream, that
    causes libpng to write PNG files with incorrect zlib header bytes.
* Fixed bug with sCAL chunk and big-endian machines (David Munro).
* Undid new code added in 1.2.6rc2 to update the color_type in
    png_set_filler().
* Added png_set_add_alpha() that updates color type.
* Revised png_set_strip_filler() to not remove alpha if color_type has alpha.
* Added makefile.hp64
* Changed projects/msvc/png32ms.def to scripts/png32ms.def in makefile.cygwin