Add check_flatness keyword to HZ and format

[pkofod]

See #174 (comment)

I'm not sure the check does what it's intended to do, so I'm turning it off and giving the possibility of turning it back on.

[pkofod]

I should have not done the format in this pr, but... I just add a keyword and a test. That said, of course the tests do not pass on CI 😵

[pkofod]

I should have not done the format in this pr, but... I just add a keyword and a test. That said, of course the tests do not pass on CI 😵

i see, it also fails when in a test set locally but not when run by hand 👍 what a gift that keeps on giving :)

[pkofod]

I should have not done the format in this pr, but... I just add a keyword and a test. That said, of course the tests do not pass on CI 😵

i see, it also fails when in a test set locally but not when run by hand 👍 what a gift that keeps on giving :)

nevermind, just seems like issues.jl was not loaded and the same test had already been added as broken somewhere else

[pkofod]

This is just a quick'n'dirty "solution". #180 is a re-implementation as mine in NLSolvers.jl and I want to compare them later, but I don't think the flatness check is currently correct so I think we should turn it off by default