----------------------- AmigaOS 3.2 project --------------------------

png.datatype 47.1 (24.4.2020)

- Adapted from the sources of OS 4.x png.datatype 53.10, kindly 
  provided by Oliver Roberts upon request of James Jacobs. Thanks 
  Oliver and James!

- Now the zlib and libpng linker libraries are automatically built in 
  their respective subdirectories by the main GNUmakefile.

- The main GNUmakefile now also builds the PNG descriptor to be copied 
  into DEVS:DataTypes. This requires MakeDT.rexx to be present in 
  V:aug/makedt.

png.datatype 47.2 (6.5.2020)

- Fixed a bug that caused the datatype to always fail when trying to 
  save a picture to disk in PNG format.

- The PNG descriptor is no longer generated by the build process along 
  with the datatype itself, since this is not actually necessary.

- Enabled experimental optimization of the generated code. Not sure if 
  this made it any faster, but at least the binary is now 12444 bytes 
  shorter.

png.datatype 47.3 (7.5.2020)

- The main GNUmakefile does now specify optimization options the 
  proper way; thanks to Olaf for the useful information on how that 
  should be done.

- Removed "possibly uninitialized variable..." warnings from the 
  sources of the datatype and zlib.

- No functional changes.