Merge branch 'release/0.0.66' into develop
npm: 0.0.65 -> 0.0.66
src: add instance method 'leftCols()'
test: add instance method 'leftCols()' testings
readme: add instance method 'leftCols()' api
lint: add some files for linting pass
npm: 0.0.66 -> 0.0.67
Merge branch 'release/0.0.67'