GitLab

* Change VS -> MinGW for CRAN

* Documentation to switch to MinGW by default

* Force cmake to run twice

* Try again dual build for Rtools

* Switch to cmake for building twice

* Try with Visual Studio as default, MinGW as fallback

* Try to remove VS appropriately when failing

* Attempt to get rid of build folder first

* Switch to unlink from rm rf

* Change lib_folder correctly when VS fails

* Add README updates from Microsoft/LightGBM@1c8355c

* Update default compiler doc and add GPU online install doc

* Better GPU doc

* add draft of RF.

* fix score bugs.

* fix scores.

* fix tests.

* update document

* fix GetPredictAt

* add keep_training_booster

* use model string

* reset handle; free dataset

thanks for building in early_stopping! super useful.

fixed english mistakes

* setup.py custom install & sdist

* global data_files

* fix install rule

* fix pylint

* clean codes

* use distutils.command

* overwrite install_lib

* add copy_files; fix pylint

* install openmpi only TASK=mpi

* add TASK=sdist & bdist

* setuptools.command instead of distutils

* add METHOD=pip for gpu test

* use openmpi to install gcc

* set OpenCL_INCLUDE_DIR & BOOST_ROOT

* update doc

* export BOOST_ROOT

* update doc

* update doc

* update doc

* support travis osx

* add task=pip

* add osx task=pip

* fix gpu build

* add if-else task

* fix if-else task

eval_at has been broken after e465f92a.
This commit will fix eval_at.