Allow different paragraph breaks in fromHtml()

- Separate block-level elements with different numbers of newline
  characters according to the user specified option flag.

- Parse the ALIGN attribute and the CSS TEXT-ALIGN property to handle text
  alignment.

- Rename "header" to the correct term "heading"

Change-Id: I446fa97155e761623a1da6632a0d872a5e47e8af