Fixes #75. * Fixed spelling of "Succeeded" in `check`. * Added a flag to `check` to determine whether or not to print. * Use sys.stdout.write to print "Adding line %d..." every 1000 waterpoints so `check` print appears on same line. * Added before and after messages to make things doubly clear.

This overrides the docstring (which I don't think you intended). Could you turn this into a comment and move after the docstring (amend commit)?