- whitespace-sensitive formatting
- respect css `display: block`/`white-space: pre` (data from [`html-styles`](https://github.com/marionebl/html-styles))
- support magic comment (`<!-- display: block -->`)
- add an option to specify whitespace sensitivity (`--html-whitespace-sensitivity <css|strict|ignore>`)
- magic comments take precedence
- (default) `css`: respect default css style (safe in the most cases)
- `strict`: every node is considered whitespace sensitive (the safest)
- `ignore`: every node is considered whitespace insensitive (dangerous, the original behavior)
- inline inline-tags
- support ie conditional comment (`<!--[if IE]><![endif]-->`)
- indent the script/style content
- no inconsistent output for 2+ attributes
- force break tag if there're multiline attributes
- switch to [`htmlparser2`](https://github.com/fb55/htmlparser2)
- no need to fork
- won't generate pseudo nodes ([`parse5` will](https://github.com/prettier/prettier/issues/5098#issuecomment-423055181))
- should be [faster](https://github.com/fb55/htmlparser2#performance)
- support custom self-closing tags
- support HTML entities
- remove extra trailing newline for `<template>`
- distinguish empty/empty-string attributes (`<tag x>`/`<tag x="">`)
- rename `--parser parse5` with `--parser html`
- enable `html` since 1.15, which means it's enabled by default if you install the dev version from GitHub after this PR merged.