make max_iter kwarg

[elbeejay]

PR closes #31 by making a max_iter key-word argument to allow people to specify a higher iteration threshold for target-time simulations.

Also adds verbose key-word arguments to every function which has a print statement. Eventually hope to establish some sort of logging functionality (re: #32) but still thinking through the best way to implement that.

Opened #34 to address loss of test coverage due to these new verbose flags and no explicit tests for whether or not print statements are being called.

Finally, incremented the most minor version number here as this PR does not modify the underlying walk behavior or anything to do with the particles really, except for making the iteration limit more flexible.

[codecov]

Codecov Report

Merging #33 (6eeca40) into master (9aa3ed7) will decrease coverage by 0.17%.
The diff coverage is 60.00%.

@@            Coverage Diff             @@
##           master      #33      +/-   ##
==========================================
- Coverage   97.84%   97.66%   -0.18%     
==========================================
  Files           2        2              
  Lines         556      557       +1     
==========================================
  Hits          544      544              
- Misses         12       13       +1     

Impacted Files	Coverage Δ
dorado/particle_track.py	97.02% <50.00%> (-0.23%)	⬇️
dorado/lagrangian_walker.py	100.00% <100.00%> (ø)

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