#include <State.h>
State for applying a second order section to a sample using Direct Form II
Difference equation:
v[n] = x[n] - (a1/a0)*v[n-1] - (a2/a0)*v[n-2] y(n) = (b0/a0)*v[n] + (b1/a0)*v[n-1] + (b2/a0)*v[n-2]