Performance improvements

[IkeVoodoo]

This would slightly differ from the original implementation, however, if we replace all instances of

x += y * z;

with

x = Math.fma(y, z, x);

we can get a huge speedup, for example, replacing all occurrences of this in just the de.bwaldvogel.liblinear.SparseOperator class we can get a 2x speed up on machines with FMA enabled.

However it would require switching to Java 9.