Add cobra with scipy

[Annixious]

Changed cobra implementation by using scipy package.

[codecov[bot]]

Codecov Report

Attention: 4 lines in your changes are missing coverage. Please review.

Comparison is base (00aa77b) 57.85% compared to head (a4b3cbc) 57.95%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## devel #321 +/- ## ========================================== + Coverage 57.85% 57.95% +0.10% ========================================== Files 39 39 Lines 2520 2538 +18 ========================================== + Hits 1458 1471 +13 - Misses 1062 1067 +5 ``` | [Files](https://app.codecov.io/gh/netZoo/netZooPy/pull/321?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=netZoo) | Coverage Δ | | |---|---|---| | [netZooPy/cobra/cobra.py](https://app.codecov.io/gh/netZoo/netZooPy/pull/321?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=netZoo#diff-bmV0Wm9vUHkvY29icmEvY29icmEucHk=) | `87.50% <86.66%> (-12.50%)` | :arrow_down: | ... and [2 files with indirect coverage changes](https://app.codecov.io/gh/netZoo/netZooPy/pull/321/indirect-changes?src=pr&el=tree-more&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=netZoo)

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[marouenbg]

@violafanfani all good to me for merging. @Annixious's PR improves runtime of COBRA. Including @soelmicheletti for the record.