Fixed incorrect instance shuffling algorithm.

[hpxro7]

There was a minor implementation bug in base/instances.go in regards to the Shuffle() method on Instances that causes it to create a non-uniform distribution of shuffle permutations. I've changed it to implement the correct Fisher-Yates algorithm.

[penberg]

Travis CI thinks gonum's mat64 is broken. Did "go test" work on your local machine?

# github.com/gonum/matrix/mat64
../../gonum/matrix/mat64/dense_arithmetic.go:339: undefined: blas.RowMajor
../../gonum/matrix/mat64/dense_arithmetic.go:346: too many arguments in call to blasEngine.Dgemm
../../gonum/matrix/mat64/lq.go:117: undefined: blas.ColMajor
../../gonum/matrix/mat64/lq.go:122: too many arguments in call to blasEngine.Dgemv
../../gonum/matrix/mat64/lq.go:136: undefined: blas.ColMajor
../../gonum/matrix/mat64/lq.go:141: too many arguments in call to blasEngine.Dgemv
../../gonum/matrix/mat64/lq.go:174: undefined: blas.RowMajor
../../gonum/matrix/mat64/lq.go:178: too many arguments in call to blasEngine.Dtrsm
../../gonum/matrix/mat64/vec.go:84: undefined: blas.RowMajor
../../gonum/matrix/mat64/vec.go:92: too many arguments in call to blasEngine.Dgemv
../../gonum/matrix/mat64/vec.go:92: too many errors

The command "go get -v ./..." failed and exited with 2 during .

Your build has been stopped.

[penberg]

I don't know how pedantic we are with these but this is diff noise that can be fixed by gofmt.

[lazywei]

I think this is because some people use gofmt while others use goimport. The order of the two package is somehow a little different.
Personally, I use goimport becasue it can also handle import.

[hpxro7]

go test passes on my machine.

As far as the diff noise goes, @lazywei is right, I do use goimport. As a side note, gofmt does not seem to collapse the empty blankline space between the local/external package imports if its already there.

[penberg]

Looks like a gonum/matrix problem.

[kortschak]

We're waiting on review, but it is fixed in this change.

[hpxro7]

Roger that. Thanks!

[penberg]

Could someone try to trigger Travis CI build for this pull request? It should work now.

[sjwhitworth]

Done. Builds now I think.

[penberg]

Great, maybe someone can merge this then. 😄