GitLab

* [ci] fixed cpplint errors about string& members

* add constructor

* [ci] fixed cpplint errors about string& members

* add constructor

* refix
Co-authored-by: guolinke <guolin.ke@outlook.com>

* [R-package] Introduced define LGB_BUILD_R to control compilation of lib_lightgbm for the R package

* fixed comment

* switched to cmake options

* fixed typo

* speed up for const hessian

* rename template

* some refactorings

* refine

* refine

* simplify codes

* fix random in feature histogram

* code refine

* refine

* try fix

* make gcc happy

* remove timer

* rollback some changes

* more templates

* fix a bug

* reduce the cost of timer

* fix gpu

* fix bug

* fix gpu

* added all necessary includes - fixed build/include_what_you_use error

* fixed the order of includes (build/include_order)

* decode error description

* added break line char in log massages