Apply a binary operation function to each field of two input structures, including substructure fields of any level.
C = STRUCTFUN2(FUN, A, B) applies the function specified by FUN to each field of structures A and B, and returns the results in array C.

Examples:
s1 = struct; s1.a = 1; s1.b = 2; s1.c = struct; s1.c.a = 3;
s2 = struct; s2.a = 0; s2.b = 2; s2.c = struct; s2.c.a = -3;
s3 = structfun2(@plus, s1, s2);