neomake#utils#WideMessage: replace newlines with spaces (#1296)
neomake#utils#WideMessage: replace newlines with spaces (#1296)

This accompanies the fix for writegood accidentally added to 90c3393.

Before this newlines would be removed altogether, but the reason for
that should be fixed somewhere else:

> This is here because it is possible for some error messages to
> begin with \n which will cause a "press enter" prompt.
codeinabox/neomake,neomake/neomake,euclio/neomake,euclio/neomake,nerdrew/neomake,neomake/neomake,nerdrew/neomake