v1.0.23

• improve empty image anchor cleanup so it handles decorative svgs
• significant improvements to code block normalization and language detection. Now validates against languages supported by highlight.js (fixing issue where you could end up with things such as "default" or "container" for code fence language).
• set alias for text/plaintext/plain language to txt (because txt is the only one that disables syntax highlighting in both the joplin markdown editor and viewer).