src: add 'CPartialPivLU' object
src: add some instance method for CPartialPivLU

instance methods permutationP(), matrixL(), matrixU(), and solve()
test: add some testings

instance method permutationP(), matrixL(), matrixU(), and solve()
readme: add 'CPartialPivLU' api
readme: add instance method 'partialPivLu()' api
lint: add some files for linting pass
test: add some testings for 'CPartialPivLU'