Add GitHub templates and changelog

[dominik-zeglen]

I want to merge this because it adds changelog to keep track of the updates and github config to help keeping things tidy in the repository.

[codecov]

Codecov Report

Merging #97 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master      #97   +/-   ##
=======================================
  Coverage   88.02%   88.02%           
=======================================
  Files         699      699           
  Lines       11053    11053           
  Branches      927      927           
=======================================
  Hits         9729     9729           
  Misses       1169     1169           
  Partials      155      155

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