ENH: fixed pmute function to copy elements instead
JL: new smol_inds function TAG: allocate-fill grid

also, tried to write new function for sgrid_2 that pre-allocates and
fills instead of doing the vcat, but it was slower and used more memory

This is a commit to store it for later, in case for some reason we want
it
Merge branch 'master' of github.com:sternSargentRA/Smolyak.jl
Merge branch 'master' of github.com:sternSargentRA/Smolyak.jl
PY: naive build B method