Hvconfounds

Eliminated the `numpy.linalg.svd` call originating from `scipy.linalg.svd` by solving the equivalent eigenvalue problem `scipy.linalg.eigh` of the inner product matrix, staying in the scipy module, and hence increasing stability. This is particularly the case if `numpy` is not compiled against `lapack`, but against `lapack-lite`.

This solves issue #152.