Package fop and its dependencies in the resources
Call the local copy of fop
Merge WrappedXMLRenderer and Docbook renderer.

As we're calling out to fop in the XSLFORenderer, rather than
constructing a Document, it seems unlikely that there will be a new
renderer which needs this.
Remove WrappedStreamRenderer.

It seems unlikely that anything other than RawRenderer will use this.
Correctly implement heading levels in DocbookRenderer.

The current section of interest is now the head of a stack which is
pushed to whenever a lower-level heading is encountered, and popped from
(and the old head appended to its containing section) when a
higher-level heading is encountered.

This has the knock-on effect of XSL-FO, rtf, PostScript, and PDF now
doing headings properly.
Remove debugging exception from DocbookRenderer
Fix rendering of unexpanded MacroNodes in HTML
ltrim and rtrim whitespace from plaintext sequences in Visitor
Do link error handling in ASTRenderer by default
Initialise FOP_DIR statically in XSLFORenderer
Initial version of .docx renderer.

This pulls in docx4j as a run- and build-time dependency, and slf4j as a
run-time dependency.
Fix NullPointerException on saving pages introduced in d434f4d
Fix rendering regression introduced in 28fabbe.

This made constructs like "//\w+//" render as "////", which is incorrect.
Update rendering tests to reflect changes to whitespace made in 28fabbe
Checkstyle fixes
Implement the table alignment directive in the docx renderer
Fix code display in docx renderer
Fix null pointer exception in Docx initialisation introduced by 06e5883
Add rendering extension tests for unexpanded macros and table valignment directives
Add tests for reading the renderer registry