Quickbook: New branch for development.

From now on this will be my development branch.
Quickbook: Don't require newlines at end of grammar.
Quickbook: 'alpha' version.
Quickbook: Remove accidentally commited test result.
Quickbook: Small code clean ups.
Quickbook: Trying to clarify to myself the doc info stuff.
Quickbook: New tests. Mostly state tracking.
Quickbook: Just use doc_type for main document.
Quickbook: No need to store quickbook version, as it's ignored in included files.
Quickbook: Alternative tst that's cheaper to copy.
Quickbook: Clearer tracking of state in templates and files.

Not quite exception safe, since macros can't be swapped.
Quickbook: Port the combined include/import from old branch.
Quickbook: Scope templates in `include` in 1.6
Quickbook: Import templates+macros from quickbook file in 1.6
Quickbook: Include code file in 1.6.
Quickbook: Nested documents in 1.6.

If an included file has a docinfo block, use that docinfo. I'm not
entirely sure if the nested file be treated as if it's completely
standalone - i.e. should macros and templates defined in the parent be
used?

Also, there's some odd behaviour in quickbook if the docinfo block in an
included file has a parse error. It just goes back to the start and
parses as a file without a docinfo block. I think it would be better if
this was a hard error, but what should happen in someone has defined a
template with the same name as a docinfo block? That's actually valid in
existing quickbook, so the dodgy docinfo block might just be a template
call.
Quickbook: merge from trunk.
Quickbook: Overwrite duplicate macros in 1.6
Quickbook: Better error messages when loading a file.
Quickbook: fix repeated 'warning' in version not defined message.