Bug fixes, better test coverage

[computablee]

Which issue are you addressing?

Partially addresses #45

How have you addressed the issue?

This PR introduces calls to DotMP that test several currently untested code paths, especially in Parallel.FixArgs. Additionally, one of the updated tests caught a bug in GetNumThreads, so this PR introduces a bug fix for that.

How have you tested your patch?

This is a testing PR :)

[codecov[bot]]

Codecov Report

Attention: 1 lines in your changes are missing coverage. Please review.

Comparison is base (2d604ef) 93.28% compared to head (943349c) 95.45%. Report is 1 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #88 +/- ## ========================================== + Coverage 93.28% 95.45% +2.16% ========================================== Files 12 12 Lines 1102 1099 -3 Branches 101 101 ========================================== + Hits 1028 1049 +21 + Misses 54 34 -20 + Partials 20 16 -4 ``` | [Files](https://app.codecov.io/gh/computablee/DotMP/pull/88?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Phillip+Allen+Lane) | Coverage Δ | | |---|---|---| | [DotMP/Parallel.cs](https://app.codecov.io/gh/computablee/DotMP/pull/88?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Phillip+Allen+Lane#diff-RG90TVAvUGFyYWxsZWwuY3M=) | `91.94% <75.00%> (+5.00%)` | :arrow_up: |

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[computablee]

Ignoring the failing codecov patch action. There's something funky going on with coverlet, looks to be a bug.