Optional glam feature

[OhKannaDuh]

Add an optional glam feature flag for less friction on type coercion. Because of Rust's orphan rules, this is the type of thing that can only live in this library, outside of an intermediate type being implemented. This came about because I was thinking about what was discussed in this issue: redstrate/Kawari#323

There a few options:

• We could do it this way, by allow Physis to optionally integrate with glam.
• We could implement an intermediary newtype that wraps Affine3a and implements From<Transformation>
• We could have a converter function, similar to what is in the linked issue. fn physis_transform_to_affine3a(transformation: &Transformation) -> Affine3A

[redstrate]

We could do it this way, by allow Physis to optionally integrate with glam.

This is the method I was thinking of, I was under the assumption you could maybe use Into instead but really I think enough people would find this useful as an optional thing.

[redstrate]

Thanks! LGTM is very much appreciated (along with the tests as well)

[OhKannaDuh]

We could do it this way, by allow Physis to optionally integrate with glam.

This is the method I was thinking of, I was under the assumption you could maybe use Into instead but really I think enough people would find this useful as an optional thing.

You get Into for free from a From impl