Added more Scipy integrators to handle stiff problems

[mkaguer]

Currently there is only one scipy integrator classes that uses RK45. I created a general integrator class that uses RK45 by default called ScipyIntegrator, this is the parent class. Then, I created child classes that inherit from this class but pass different solvers. I added two more solvers currently not available, BDF and LSODA. These solvers work for stiff problems.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.3%. Comparing base (dfc0387) to head (953c38d).
⚠️ Report is 13 commits behind head on dev.

Additional details and impacted files

@@          Coverage Diff          @@
##             dev   #2880   +/-   ##
=====================================
  Coverage   90.3%   90.3%           
=====================================
  Files        148     148           
  Lines       8623    8633   +10     
=====================================
+ Hits        7789    7799   +10     
  Misses       834     834           

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[ma-sadeghi]

Nice, can you add some unit tests?

[mkaguer]

Nice, can you add some unit tests?

Yea, I'll do that this week when I get back to work!

[mleot]

I also have motivation to add more integrators to OpenPNM. I can help out with writing some of these unit tests.

[jgostick]

Hey @mkaguer, are we still interested in merging this PR? I have refreshed it by merge the latest dev into it. It now passes the non-mac tests. Should we merge it? Any change you could address @ma-sadeghi's request to add a test or two?

[TKlokgieters]

@jgostick Any chance this can be merged? As far as I can tell the unit tests were committed in/with [a6cc209] .
I'd also be interested in solving stiff problems using the different integrator methods.

If anything is missing I'd be happy to help.