* Added checks to setRotation() and setLocation() to prevent performance decrease. * Commented out the sanityCheck() in pool destructor, it is only usefull for debugging and slows down the engine destruction massively.

This demonstrates the use of PNG_USER_CONFIG and pngusr.h

To build a minimal write-only encoder, run
    gather.sh  # to collect needed files from pngminus, libpng, and zlib
    make -f makefile.std