Touying 0.4.0

Features

• feat: support #footnote[] for all themes. #26
• feat: access subslide and repeat in footer and header by self => self.subslide. #21
• feat: support numbered theorem environments by ctheorems.
• feat: support numbering for sections and subsections.

Fixes

• fix: make nested includes work correctly.
• fix: disable multi-page slides from creating the same section multiple times. #23

Breaking changes

• refactor: remove self.padding and add self.full-header self.full-footer config.