- Add Content::Key as proxy to Language::try_msg
- Add Content::Attr as proxy to Language::try_attr
- Extend ItemKey::TagExamples so it includes base asset id
- Implement ItemDesc::l10n using new Content variants
- Add all_items_expect() function to grab all items, because
try_all_item_defs() covers only items in asset folder.
Required assets will go in next commit
- Add the comment that recommends avoiding all `get_variation` methods.
- Add the comment that recommends avoiding Content with random i18n.
- Improve `get_content` docs.
