Fix for dplyr 1.0.0

[romainfrancois]

This is 2 fixes that make this package pass against dplyr 1.0.0, this should also work against previous versions of dplyr so don't hesitate to release survminer.

• This uses group_by() instead of group_by_() which is deprecated
• This puts the extra "surv_group_by" class first where it is supposed to be instead of last, which messes up with some internal processing from vctrs.

[LindaDansereau]

Hello,
Related to this fix I recently used ggsurvplot_facet and got the following warnings in connection with updates to tibble and dplyr. I am using Survminer package v. 0.4.7 and have tried using v.0.4.7.999 as well.

Thank you!

[[1]]

message: as.tibble() is deprecated as of tibble 2.0.0.
Please use as_tibble() instead.
The signature and semantics have changed, see ?as_tibble.
This warning is displayed once every 8 hours.
backtrace:
6. survminer::ggsurvplot_facet(...)
3. survminer::surv_pvalue(...)
3. dplyr::bind_rows(.)
11. tibble::as.tibble(.)

[[2]]

message: select_() is deprecated as of dplyr 0.7.0.
Please use select() instead.
This warning is displayed once every 8 hours.
backtrace:
6. survminer::ggsurvplot_facet(...)
10. dplyr::select_(., .dots = facet.by)
15. dplyr:::lazy_deprec("select", hint = FALSE)

[KaiAragaki]

@LindaDansereau I have noticed the as.tibble message as well and have submitted a PR (#546) to hopefully suppress this particular warning. The select_ -> select conversion will probably take more thought than a simple drop in, I think.