Log Message:
Update to 1.5.1:

Version 1.5.1beta10 [January 27, 2010]
  Fixed incorrect examples of callback prototypes in the manual, that were
    introduced in libpng-1.0.0.
  In addition the order of the png_get_uint macros with respect to the
    relevant function definitions has been reversed.  This helps the
    preprocessing of the symbol files be more robust.  Furthermore, the
    symbol file preprocessing now uses -DPNG_NO_USE_READ_MACROS even when
    the library may actually be built with PNG_USE_READ_MACROS; this stops
    the read macros interfering with the symbol file format.
  Made the manual, synopses, and function prototypes use the function
    argument names file_gamma, int_file_gamma, and srgb_intent consistently.

Version 1.5.1beta11 [January 28, 2011]
  Changed PNG_UNUSED from "param=param;" to "{if(param){}}".
  Corrected local variable type in new API png_process_data_skip()
    The type was self-evidently incorrect but only causes problems on 64 bit
    architectures.
  Added transform tests to pngvalid and simplified the arguments.

Version 1.5.1rc01 [January 29, 2011]
  No changes.

Version 1.5.1rc02 [January 31, 2011]
  Added a request in the manual that applications do not use "png_" or
    "PNG_" to begin any of their own symbols.
  Changed PNG_UNUSED to "(void)param;" and updated the commentary in \ 
pngpriv.h

Version 1.5.1 [February 3, 2011]
  No changes.