Separate nullspace and nearnullspace

[cmdoug]

Attempt to fix #371 reported by @echarala.

[prj-]

LGTM, @echarala, could you please confirm this fixes your issue?

[echarala]

Yes, it should. I will try it in my problem. Nice fix, guys!

[cmdoug]

@prj- note that the CI pipeline didn’t auto-run for this PR yet. It passes make check on my end, though.

[prj-]

Yeah, there is no reason to have it fail make check, since the code (or the combination of both null spaces) is largely untested. It would be nice to have a minimalist example that combines both and that was previously failing, but I'm guessing it may be a little bit difficult to extract from your code, @echarala? BTW, I'm waiting on your confirmation to get this integrated, so please let us know.