LDLt factorization for full matrices

[zdenek_hurak]

Shouldn't `bunchkaufman` be actually named `ldlt`?

I am just musing over the choise of the name bunchkaufman for the bunkaufman function. If I understand it correctly, the function provides an implementation of an algorithm for LDLᵀ factorization of a symmetric and in general indefinite matrix. The thing is that there is a dedicated function for performing the LDLᵀ factorization – it is named ldlt. It seems to me that the only difference is that ldlt function works for either dense tridiagonal or sparse matrices, while bunchkaufman works for den…