getproperty for SuiteSparse.UMFPACK.UmfpackLU always extracts all fields #827
Description
The getproperty method for UmfpackLU extracts all fields for the object, then discards the ones that weren't requested. This is clearly suboptimal for performance, an issue which I've run into here.
Umfpack should allow extracting just one of the fields of the UmfpackLU structure by passing in null values for the unwanted arguments--see top of page 94 in the Umfpack docs (PDF). It would be great to modify the getproperty and/or extract_umf methods to allow extracting just one field at a time to avoid unnecessary allocations.
(this issue was moved here from https://github.com/JuliaLinearAlgebra/SuiteSparse.jl/issues/9)