v0.13.0

What's Changed

• refactor(app): move the reader's state out of run_inner into a Reader struct by @borghei in #41
• feat(mermaid): draw sequence diagrams on the character grid by @borghei in #42
• fix: Shift+Tab switches tabs; resizing under an overlay re-lays out the document by @borghei in #43
• chore(release): v0.13.0 by @borghei in #44

Full Changelog: v0.12.0...v0.13.0