Merge pull request #571 from bgreenwell/master

New deforest() function for removing trees from a fitted random forest

remove GPL files and keep only MIT licenced files

CRAN release 0.12.1

Merge pull request #321 from imbs-hl/fix_case_weights

Fix case weights check in cpp version

Merge pull request #242 from imbs-hl/issue239

Fix #239

Merge pull request #57 from imbs-hl/win_threads

Windows multithreading support

release new CRAN version

change version in news file