Add box to fresnel visualization

[marjanalbooyeh]

This PR adds the simulation box to the rendered images.

[codecov]

Codecov Report

Merging #55 (705ef73) into master (543a2c6) will increase coverage by 0.02%.
The diff coverage is 97.05%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master      #55      +/-   ##
==========================================
+ Coverage   96.03%   96.06%   +0.02%     
==========================================
  Files           8        8              
  Lines         606      636      +30     
==========================================
+ Hits          582      611      +29     
- Misses         24       25       +1     

Files Changed	Coverage Δ
cmeutils/visualize.py	97.32% <97.05%> (-0.13%)	⬇️

[chrisjonesBSU]

LGTM, thanks! We just need a couple unit tests that checks if height is being set to the right values, and that self.scene.geometry contain the right objects depending on show_box