Docstring fix for `savetxt`
Merge pull request #4574 from ggventurini/master

DOC: Docstring fix for `savetxt` (minor change)
DOC: clarify savetxt delimiter and newline docstring

newline and delimiter can be strings not only single characters
TST: add more regression testing related to https://github.com/numpy/numpy/issues/4733
Merge pull request #4748 from argriffing/more-linalg-regression-testing

TST: add more regression testing related to https://github.com/numpy/numpy/issues/4733
STY: Use `.astype`'s `copy` kwarg in `np.tri`

Replace an explicit type check with setting `copy=False` in call to `astype`.
Merge pull request #4750 from jaimefrio/tri-sty

STY: Use `.astype`'s `copy` kwarg in `np.tri`