ae409c2cd1732f8889949d5f10865703285441b9: Fixes a dumb mistake I made that caused imported shape keys to be completely incorrect for anything but the first shape key per mesh. Didn't notice it originally because i happened to be testing with the first key, whoops.
c11519c95ef223bd4964bfd94739dfecc470012a: The material section and the material group in the further content section were sharing an ID. Just scoping the further content with a pushed id.
655d1722c18fbd24b5a569129c6005c439d7102d: bug report. some bgpart models have attribute masks but no attributes. this just makes that fail-soft, but not sure if it's garbage data or a data union which they use for other things on attribute-less models.
a38db004787d6474b557760e95f1bed2a5b09fd2: adds documentation links to import and export. they're both links to sections on https://github.com/xivdev/Penumbra/wiki/Model-IO, which i'll be expanding over time.
requires https://github.com/Ottermandias/OtterGui/pull/6
Another collection of smaller fixes.