refactor: split stuff from src/ast.rs into smaller modules

This only moves things around, to avoid huge source code modules. It
doesn't rename functions, add unit tests, or similar.

* src/datafiles.rs: DataFile, DataFiles
* src/metata.rs: Metadata
* src/panhelper.rs: functions for querying Pandoc Attrs
* src/policy.rs: the get_basedir_from function; place for later policy
  functions
* src/typeset.rs: functions to produce Pandoc AST nodes
* srv/visitor/*: various MutVisitor implementations for traversing
  ASTs, and their helper functions

1 files changed, 17 insertions, 0 deletions

diff --git a/src/visitor/mod.rs b/src/visitor/mod.rs
new file mode 100644
index 0000000..95bf2b1
--- /dev/null
+++ b/src/visitor/mod.rs
@@ -0,0 +1,17 @@
+mod block_class;
+pub use block_class::BlockClassVisitor;
+
+mod datafiles;
+
+mod image;
+pub use image::ImageVisitor;
+
+mod linting;
+pub use linting::LintingVisitor;
+
+mod structure;
+pub use structure::Element;
+pub use structure::StructureVisitor;
+
+mod typesetting;
+pub use typesetting::TypesettingVisitor;