sorting bounds checks: wrapping a function definition does nothing.

Sortperm on Float64 arrays is now 37% faster than it used to be since
I've actually removed the bounds checks in nans2left and nans2right.
I tried various ways to wrap the lt(::Perm,a,b) call in `@inbounds`
but all approaches caused significant slow downs.
Merge branch 'master' of github.com:JuliaLang/julia

Conflicts:
	base/ordering.jl