Add parse structure for testing

[Pikachu920]

Description

Adds a parse structure to allow testing structures for errors.

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Target Minecraft Versions: any Requirements: none Related Issues: none

[Pikachu920]

rather than allowing just a single section, i was thinking it might be better to parse anything in the code section a separate script (which can contain multiple structures). that way you can test for errors that depend on multiple structures are thrown (e.g. defining two commands of the same name).