png transformation

image.h now loads png's that animation.h will use
first slot created (0=default)
Sheldon uses now pngs for its screen
lib&all seems to be fixed, hunting down segfaults
theoretically working...
pixel loop is working, but SFML crashes
opening png with pnglib

looking forward to read them ! haha
opening PNG with pnglib

et maintenant, ça compile
animations are working fine (no segfault)
Merge William branch