Add contributors in README and GUI

[beorostica]

This pull request is intended to resolve issue #191

[codecov]

Codecov Report

Merging #247 (0502143) into master (7c63ab7) will decrease coverage by 1.06%.
The diff coverage is n/a.

❗ Current head 0502143 differs from pull request most recent head 2113030. Consider uploading reports for the commit 2113030 to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #247      +/-   ##
==========================================
- Coverage   90.26%   89.21%   -1.06%     
==========================================
  Files          33       33              
  Lines        2291     2290       -1     
==========================================
- Hits         2068     2043      -25     
- Misses        223      247      +24     

Flag	Coverage Δ
core	87.05% <ø> (-1.99%)	⬇️
io	86.14% <ø> (-0.31%)	⬇️
komamri	94.09% <ø> (ø)
plots	93.80% <ø> (ø)

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see 4 files with indirect coverage changes