Change data.table return statements

[nikosbosse]

update return statements such that data.table contents are displayed immediately

[codecov]

Codecov Report

Merging #142 (ae057d5) into master (03fc81c) will not change coverage.
The diff coverage is 61.53%.

❗ Current head ae057d5 differs from pull request most recent head 390751d. Consider uploading reports for the commit 390751d to get more accurate results

@@           Coverage Diff           @@
##           master     #142   +/-   ##
=======================================
  Coverage   48.44%   48.44%           
=======================================
  Files          18       18           
  Lines        1348     1348           
=======================================
  Hits          653      653           
  Misses        695      695           

Impacted Files	Coverage Δ
R/utils_data_handling.R	72.64% <54.54%> (ø)
R/pairwise-comparisons.R	42.36% <100.00%> (ø)

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