[libpng15] Bump version to 1.5.29beta01

ANNOUNCE

@@ -1,56 +1,32 @@
 
-Libpng 1.5.28 - December 29, 2016
+Libpng 1.5.29beta01 - December 30, 2016
 
-This is a public release of libpng, intended for use in production codes.
+This is not intended to be a public release.  It will be replaced
+within a few weeks by a public version or by another test version.
 
 Files available for download:
 
 Source files with LF line endings (for Unix/Linux) and with a
 "configure" script
 
-   libpng-1.5.28.tar.xz (LZMA-compressed, recommended)
-   libpng-1.5.28.tar.gz
+   1.5.29beta01.tar.xz (LZMA-compressed, recommended)
+   1.5.29beta01.tar.gz
 
 Source files with CRLF line endings (for Windows), without the
 "configure" script
 
-   lpng1528.7z  (LZMA-compressed, recommended)
-   lpng1528.zip
+   lp1529b01.7z  (LZMA-compressed, recommended)
+   lp1529b01.zip
 
 Other information:
 
-   libpng-1.5.28-README.txt
-   libpng-1.5.28-LICENSE.txt
-   libpng-1.5.28-*.asc (armored detached GPG signatures)
+   1.5.29beta01-README.txt
+   1.5.29beta01-LICENSE.txt
+   libpng-1.5.29beta01-*.asc (armored detached GPG signatures)
 
-Changes since the last public release (1.5.27):
+Changes since the last public release (1.5.28):
 
-  Merged with current libpng16 gregbook, pngvalid.c, pngtest.c, pngminim,
-    pngminus
-  Added "Common linking failures" section to INSTALL.
-  Fixed undefined behavior in png_push_save_buffer(). Do not call
-    memcpy() with a null source, even if count is zero (Leon Scroggins III).
-  Merge contrib/pngminim/*/makefile with libpng-1.6.24
-  Minor editing of INSTALL, (whitespace, added copyright line)
-  Removed the use of a macro containing the pre-processor 'defined'
-    operator.  It is unclear whether this is valid; a macro that
-    "generates" 'defined' is not permitted, but the use of the word
-    "generates" within the C90 standard seems to imply more than simple
-    substitution of an expression itself containing a well-formed defined
-    operation.
-  Previously the pngtrans.c code always resulted in an unsigned arithmetic
-    overflow. This is well defined but produces errors from clang with the
-    option to detect unsigned overflow. As the expression only gets
-    evaluated once per row in this version of libpng it is easier just
-    to rewrite it.
-  The previous version of png.c produced a signed overflow as a result of
-    both the "& 0xffff" on the most significant bits of a negative argument;
-    this converted (-1) into 65535 which resulted in a subsequent overflow.
-    Since signed overflow is undefined in C90 the code has been modified to
-    correctly calculate a signed result.  This requires changing the 'hi'
-    result parameter to a signed value.
-  Fixed a potential null pointer dereference in png_set_text_2() (bug report
-    and patch by Patrick Keshishian).
+version 1.5.29beta01 [December 30, 2016]
 
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
 (subscription required; visit