added fct_lump_inorder() function

[dan-reznik]

dear maintainer, i added my own solution to issue #187. this is my first contrib to the tidyverse and my first pull request ever. one thing missing: i don't know how to add this function to the vignette.

[batpigandme]

Hi @dan-reznik. Are you talking about the vignette here? https://github.com/tidyverse/forcats/blob/master/vignettes/forcats.Rmd

If not, the README will be built, and changes propagated as part of the pkgdown site automatically after merging.

Just for future reference, it'll be easier workflow-wise in the future if you use a branch for pull requests, rather than "master" in your fork. I'm working on a write-up for this workflow right now, but just thought I'd mention it. 👍

[dan-reznik]

Dear Mara -- I noticed fct_lump(), the "closest sibling" to the function I added (fct_lump_inorder()) is not mentioned in forcat's .Rmd vignette. So I guess I will leave it as is. Also, yes, looking fwd to your writeup on how to submit pull requests on an alternate branch.

[hadley]

Fixes #187