Update lexer code to match C++ implementation

v0.4.8

[Core] Synchronize lexer output with C++ implementation

Add diagrams in code blocks subsidiary to image insert blocks

[Core] Add support for embedding code in image insert block

The embedded code can be extracted and run through a diagram generator
such as ditaa or PlantUml.

Add tool to extract code blocks

v0.4.5

[Core] Allow specifying which code blocks to be extracted

Improve error handling and reporting

Parsing errors are reported to the operating system as error codes.

Validate DocBook output

This distribution now includes a compressed DocBook 5.1 schema, and depends on Jing to validate that generated DocBook files are valid.

Add support for multi-row/column span to regular grids

v0.4.2

[Doc] Update documentation

Multi-row / multi-coloumn spans in DocBook

v0.4.1

[Doc] Update roadmap

Refactor list handling

List handling is now aligned with upstream SAM. This also fixes a parsing corner case.

Improve fidelity of DocBook conversion

Use correct tags for tables.
Map class attribute to 'role'.

Add link support to DocBook

v0.3.7

[Doc] Start writing the SAMx book