GitLab

* [R-package] remove unused code and comments

* put check back

* other typos

* [R-package] started implementing first_metric_only

* trying stuff

* more changes

* fixed handling of multiple metrics

* fixed tests

* remove duplicate tests

* get training tests

* fixes for lgb.cv()

* fixes for lgb.cv()

* fix linting

* [R-package] [docs] fix warnings in pkgdown sitte  building

* trying to get better Travis logs

* trying to get better Travis logs

* undo testing fix

* undo testing fix

* empty commit

* [R-package] [docs] Simplified examles to cut example run time (fixes #2988)

* updated learning rates

* [R-package] made roxygen2 tags explicit and cleaned up documentation

* Apply suggestions from code review
Co-Authored-By: Nikita Titov <nekit94-08@mail.ru>

* Apply suggestions from code review
Co-Authored-By: Nikita Titov <nekit94-08@mail.ru>

* Update R-package/man/lightgbm.Rd
Co-Authored-By: Nikita Titov <nekit94-08@mail.ru>

* [R-package] moved @name to the top of roxygen blocks and removed some inaccurate information in documentation on parameters
Co-authored-by: Nikita Titov <nekit94-08@mail.ru>

* Fixed typos in docs

* Fixed inconsistencies in documentation

* Updated strategy for registering routines

* Fixed issues caused by smashing multiple functions into one Rd

* Fixed issues with documentation

* Removed VignetteBuilder and updated Rbuildignore

* Added R build artefacts to gitignore

* Added namespacing on data.table set function. Updated handling of CMakeLists file to get around CRAN check.

* Updated build instructions

* Added R build script

* Removed build_r.sh script and updated R-package install instructions