Updated IGListCollectionViewLayout to rely on layoutAttributesClass

[SirensOfTitan]

…instead of just allocating a vanilla UICollectionViewLayoutAttributes. I'm happy to add tests here, but don't really have much of an opinion either way on whether this should have an explicit test case or not.

Changes in this pull request

Issue fixed: #1134

Checklist

• All tests pass. Demo project builds and runs.
• I added tests, an experiment, or detailed why my change isn't tested.
• I added an entry to the CHANGELOG.md for any breaking changes, enhancements, or bug fixes.
• I have reviewed the contributing guide

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@SirensOfTitan has updated the pull request. View: changes

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@SirensOfTitan has updated the pull request. View: changes

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[rnystrom]

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@SirensOfTitan has updated the pull request. View: changes

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