Sparse matrix formats

Implementation of sparse BLAS (Basic Linear Algebra Subprograms) routines in Go for sparse matrix arithmetic. See http://www.netlib.org/blas/blast-forum/chapter3.pdf for more details. Includes optimised assembler implementations of key kernel operations (vector dot product and Axpy operations).

Indicative Benchmarks

Operation	Pure Go	Assembler
Dusdot (with increment/stride)	1340 ns/op	978 ns/op
Dusdot (unitary)	1215 ns/op	662 ns/op
Dusaxpy (with increment/stride)	1944 ns/op	1769 ns/op
Dusaxpy (unitary)	1091 ns/op	979 ns/op