Switch to whacko/parse5

Use parse5 automatic head/body insertion

Depend on parse5 to make proper head and body tags, use those to insert correctly into head and body of master document

Mostly removes need for  `<div hidden></div>` trick, except for the the final concatenation into main document body.

Fixes #73 html5 compatible parser?
Fixes #61 Vulcanizer inlines non-head content into head, generates incorrect HTML
Fixes #53 Vulcanize breaks SVG.
Fixes #67 Characters with accents are not properly converted/formated