add parallelization option to lioness

[laurenhsu1]

Replaced lapply with parallel::mclapply to enable running lioness on multiple cores

[marouenbg]

[codecov[bot]]

Codecov Report

Base: 55.74% // Head: 55.75% // Increases project coverage by +0.00% :tada:

Coverage data is based on head (b2dc100) compared to base (4fa7999). Patch coverage: 71.42% of modified lines in pull request are covered.

:exclamation: Current head b2dc100 differs from pull request most recent head 36c6b14. Consider uploading reports for the commit 36c6b14 to get more accurate results

Additional details and impacted files

```diff @@ Coverage Diff @@ ## devel #281 +/- ## ======================================= Coverage 55.74% 55.75% ======================================= Files 19 19 Lines 2411 2416 +5 ======================================= + Hits 1344 1347 +3 - Misses 1067 1069 +2 ``` | [Impacted Files](https://codecov.io/gh/netZoo/netZooR/pull/281?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=netZoo) | Coverage Δ | | |---|---|---| | [R/LIONESS.R](https://codecov.io/gh/netZoo/netZooR/pull/281?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=netZoo#diff-Ui9MSU9ORVNTLlI=) | `92.20% <71.42%> (-2.24%)` | :arrow_down: | Help us with your feedback. Take ten seconds to tell us [how you rate us](https://about.codecov.io/nps?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=netZoo). Have a feature suggestion? [Share it here.](https://app.codecov.io/gh/feedback/?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=netZoo)

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