* [R] fix finding R.exe with cmake on WIN when it is in PATH
* [R] appveyor config for R package
* [R] wrap the lines to make R check happier
* [R] install only binary dep-packages in appveyor
* [R] for MSVC appveyor, also build a binary for R package and keep as an artifact
* [R] fix predict contributions for data with no colnames
* [R] add a render parameter for xgb.plot.multi.trees; fixes#2628
* [R] update Rd's
* [R] remove unnecessary dep-package from R cmake install
* silence type warnings; readability
* [R] silence complaint about incomplete line at the end
* [R] initial version of xgb.plot.shap()
* [R] more work on xgb.plot.shap
* [R] enforce black font in xgb.plot.tree; fixes#2640
* [R] if feature names are available, check in predict that they are the same; fixes#2857
* [R] cran check and lint fixes
* remove tabs
* [R] add references; a test for plot.shap
