Avoid unnecessary array allocation

[i-am-the-slime]

Description of the change

Avoids reusing pushAll to implement push which saves on array allocations.

Closes #236

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Checklist:

• Added the change to the changelog's "Unreleased" section with a reference to this PR (e.g. "- Made a change (#0000)")
• Linked any existing issues or proposals that this pull request should close
• Updated or added relevant documentation
• Added a test for the contribution (if applicable)

[i-am-the-slime]

Some accidental tidy formatting, but I think it's okay

[thomashoneyman]

@i-am-the-slime If you're willing to resolve the conflicts with master I'm happy to take another look.