feat: add crate subplot-build for using Subplot from build.rs

Make it easy to generate test code from a subplot in another project's
`build.rs` script.

Move the code to load documents and generate test code from
src/bin/subplot.rs and src/bin/cli/mod.rs to src/doc.rs so it can be
used without using the subplot executable.

Make the add_search_path function public so it can be used outside its
module. The subplot executable arranged for the directory where the
markdown input file resides to be added to the search path via another
way.

Sponsored-by: pep.foundation

1 files changed, 1 insertions, 0 deletions

diff --git a/src/lib.rs b/src/lib.rs
index e818c5a..59d9fb2 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -40,6 +40,7 @@ pub use metadata::Metadata;
 
 mod doc;
 pub use doc::Document;
+pub use doc::{codegen, load_document, load_document_with_pullmark};
 
 mod style;
 pub use style::Style;