add example for srfit parallel

[chiahaoliu]

@pavoljuhas This PR is just for the ease of sharing my test on this behavior, please feel free to close if needed.

Main result from this test:

==== Rw before refinements ====
0.26614659070837554
==== Rw: Sequencial refinements ====
0.12266949912726588
0.12266949912726588
0.12266949912726588
0.12266949912726588
0.12266949912726588
==== Rw: Parallel refinements ====
0.4096894020385561
0.4096894020385561
0.4096894020385561
0.4096894020385561
0.4096894020385561

[chiahaoliu]

sequential test here

[chiahaoliu]

running in parallel

[chiahaoliu]

print rw before refinement

[codecov]

Codecov Report

Merging #57 into master will not change coverage.
The diff coverage is n/a.

@@ Coverage Diff @@## master #57 +/- ##
=======================================
Coverage 81.14% 81.14% =======================================
Files 91 91 Lines 7577 7577 =======================================
Hits 6148 6148 Misses 1429 1429

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[cadenmyers13]

@sbillinge Can we either merge or close this?

[sbillinge]

This is probably a valuable example. We may want to add it to the diffpy.cmi examples but only after cleaning and removing deprecated functions. @cadenmyers13 how did you move the examples over before? f it is not too much work let's move it over, but just make an issue for now on diffpy.cmi and link this. Leave instructions how to do the move-over and we can give it to a new student at some point. It would be good to close this when it is moved over.

[cadenmyers13]

@sbillinge Moving over is no problem. I'll duplicate the work on this PR with the new API. Then I can put it in cmi

[cadenmyers13]

@sbillinge this can be closed now. Created this cmi issue diffpy/diffpy.cmi#113

[sbillinge]

closing. replaced by diffpy/diffpy.cmi#113