replace integer-based abs() with floating point fabs() and accompanying math.h
replace integer-based abs() with floating point fabs() and accompanying math.h

pornel/imgmin,pornel/imgmin,micmro/imgmin,jibsen/imgmin,rflynn/imgmin,micmro/imgmin,pornel/imgmin,jibsen/imgmin,rflynn/imgmin,jibsen/imgmin,rflynn/imgmin,micmro/imgmin,jibsen/imgmin,pornel/imgmin,rflynn/imgmin,micmro/imgmin