0.9.9

• Add support for heading tags (#263)
• Add terminal, breakOnReturn, and group block config options (#263)
• Fix an input issue on Android with newer versions of Google Keyboard (97413bc)
• Redefine behavior of nestable block attribute (#294)
• Improve behavior when backspacing into a formatted block from a block with a leading newline (#301)
• Prevent invalid HTML from being inserted into code blocks by making code blocks terminal (5e7233b)