Export combine, a vector version of bind
Polishing of NEWS
Update README.Rmd

Two very minor spelling corrections.
Update README.Rmd

Small correction to phrasing.
Merge pull request #816 from earino/master

Small fix to spelling [ci skip]
test against my fixed version of Rcpp
more resistant to const correct version of Rcpp
Merge branch 'master' of https://github.com/hadley/dplyr
Merge branch 'master' of github.com:hadley/dplyr
Don't include grouping vars twice in do.grouped_sql

Closes #673
Ensure that do() on empty data frame returns consistent types.

Closes #625