Do not escape double or single quotes by default

[pbodnar]

This follows #176 and makes output from HTMLRenderer shorter and more human-readable - by not escaping both double and single quotes by default.

I.e. instead of "something" we want to output "something".

If required, one can still force the HTMLRenderer (or any of its descendants) to escape either type of quotes:

with HTMLRenderer(html_escape_double_quotes=True, html_escape_single_quotes=True) as renderer:
    output = renderer.render(Document('"something"'))

[pbodnar]

Done.