make Permutation's next function not modify its second argument (s), to fix compability with filter, see issue #4381
added tests to check fix of #4381
emacs mode: make @ a word character again

this is really part of the identifier, and needed for proper coloring
in some emacs versions
Fix 4412
Update win-extras paths, and fix Makefile bug
Give an error if the server was closed while blocked in accept
isperm using a BitVector indicating which values have been seen
Fold _invperm back into invperm; add tests
Merge pull request #4421 from JuliaLang/db/isperm

isperm without determining the inverse permutation
Change lu to return permutation vector instead of permutation matrix.
Merge pull request #4426 from JuliaLang/anj/lup

Change lu to return permutation vector instead of permutation matrix.
Pkg: edit should return false instead of Nothing (done by add now).
Pkg: add support for os-specific requirements [close #4323, close #4424]

Inspired by @ihnorton's https://github.com/JuliaLang/julia/pull/4424.
Merge pull request #4416 from JuliaLang/teh/subarray_strides

Fix #4412
fix #4414
Merge branch 'master' of github.com:JuliaLang/julia
Merge pull request #4382 from astrieanna/fixpermutations

Fix Permutation's `next` function to work with Filter
also fix Combinations iterator to work with things like filter
fix #4413
fix #4431