Inplace reduction functions

Inplace reduction functions (including sum!, prod!, maximum!, minimum!, all!, and any!) have been within the Base for a while. This PR exports them with a modified interface that is safe & flexible.
add documentation for sum! and friends
add an entry to NEWS.md about the reduction functions that allow pre-allocated output
add the link to 6197 in news
Merge pull request #6197 from lindahua/dh/inplacesum

Reduction functions with pre-allocated output storage.
Merge branch 'master' of github.com:JuliaLang/julia
Update package generation for changes in #6191
Typo
Merge commit '52353f7d9b' into appveyor