* Highlight fallback from extra syntaxes to the theme (close#1309)
* Warning when codeblock language is unknown and cannot be highlighted
* page/section path in codeblock language missing warning
Co-authored-by: southerntofu <southerntofu@thunix.net>
* Add line highlighting to code blocks
* Fix highlighting of lines
Apparently every line to be highlighted is provided in one chunk.
* Add more documentation to codeblock.rs
* Turn FenceIter into an Iterator
* Move Range to fence.rs
* Add tests
