Refactored `src/` and `tests/` files to be compliant to `rustfmt` #55

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See the issue related, what is done in the commits and in the changelog below.

#54

Merge into Dev Checklist

Tests for the new code
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Refactored src/ files to be compliant to rustfmt
Refactored tests/ files to be compliant to rustfmt
Disabled tests/ folder for rustfmt

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On the official rustfmt repo I've found that there's an ongoing issue open about the matrices topic.

At the moment probably an acceptable workaround could be to set rustfmt to skip all the files in tests/ folder and revert all the matrices.

@AlessandroBregoli

I've spotted 3 different kinds of notations used for rank-3 tensors; I would suggest to use the same notation for clarity and consistency.

Here the 3 notations spotted, personally I find the notation number 2 the more clean:

[
    [[ 0,  2,  3],
     [ 4,  0,  6],
     [ 7,  8,  0]],
    [[0, 12,  90],
     [ 3, 0,  40],
     [ 6, 40,  0]],
    [[ 0,  2,  3],
     [ 4,  0,  6],
     [ 44, 66, 0]]
]

[
    [
        [ 0,  2,  3],
        [ 4,  0,  6],
        [ 7,  8,  0]
    ],
    [
        [0, 12,  90],
        [ 3, 0,  40],
        [ 6, 40,  0]
    ],
    [
        [ 0,  2,  3],
        [ 4,  0,  6],
        [ 44, 66, 0]
    ],
]

[
    [[-1.0, 0.5, 0.5], [3.0, -4.0, 1.0], [0.9, 0.1, -1.0]],
    [[-6.0, 2.0, 4.0], [1.5, -2.0, 0.5], [3.0, 1.0, -4.0]],
    [[-1.0, 0.1, 0.9], [2.0, -2.5, 0.5], [0.9, 0.1, -1.0]],
]

If you agree @AlessandroBregoli I would also proceed to conform all the rank-3 tensors in tests/ to the notation number 2 listed above.

We can't use ignore option into rustfmt.toml because it is not stable yet;

on the official rustfmt repo and its issues is suggested to use the inner attribute #![rustfmt::skip] instead, which is suboptimal for this use case and is also unstable on Rust, so we can't use this neither...

At this point I would give up and use cargo +nightly fmt with only ignore enabled as a non-stable option.

Refactored `src/` and `tests/` files to be compliant to `rustfmt` #55

Description

Issues related

Merge into Dev Checklist

Changelog

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