Create loadpng.cpp
removing code from .h ...
... and putting the code at the .cpp
Update loadpng.h
Update loadpng.h
Update loadpng.cpp
loadpng compiling ok
loadpng probably working fine
finished lec 5: textures
finished reading tutorial; ready to merge in master
Merge branch 'tutorial'

Conflicts:
	Makefile
	main.cpp