Matteo Cusini

I am moving this out of the merge queue for now coz it seems that you are still missing an integratedTests PR. I saw there is a branch called `feature/lowOrderWaveEqnKernel`...

> We could change > > ``` > ( "Sneddon_smoke", > "Sneddon with horizontal fracture", > ((1, 1, 1), (2,2,1)), > 0, 1, > {"atol": 1.0E-8, "rtol": 4.0E-7 } >...

This is a singlephase case, that I am also adding as a smoke test, with a slanted fracture with hexes:  I have...

This PR can be reviewed and wrapped up.

@castelletto1, @rrsettgast, @joshua-white can someone review this PR so that I can merge it?

No, I do not recall a reason for this. I do remember that we added the `m_fluxEstimate` to help the `HydrofractureSolver` in the very first time-step after an element has...

I think this is purely a tolerance issue. We need to modify the scripts to allow for the tolerances to be different for each test in the same ats file.

@francoishamon, @klevzoff I think this is ready for a first round of comments while I am gone. Ignore the std::output which is there for @jiyer28 to validate the implementation against...

@andrembcosta I think you deleted the `integratedTests` directory...

> Should I re-create it? I think I was having some problems authenticating in the integratedTests repository. I think I have fixed it but if you have permissions problems let's...