refactor(parser): use htmlparser2 for document processing

htmlparser2 is used in favour of jquery/jsdom.

- resolves major build setup problems under windows
- improves build speed (no parsing to dom required

clean up part of the logging infrastructure and include new not-to-
verbose 'fine' level.

clean up configuration options

- remove processLayoutedOnly in favour of process: 'layouted'
- remove processFlaggedOnly in favour of process: { include: [ ... ] }
- default: process: 'all' -> process all documents
- add forceGenerateRefs (default true): override heading ids with
correctly nested ids

BREAKING CHANGE:

- due to a bug in the required marked dependency that generates ids for
headings automatically, the default behavior of the plugin is changed to
override heading ids with the properly section-prefixed form. Restore
the old behavior via forceGenerateRefs = false

Closes #1