Implement TextStyle, add javadocs
Fix up TextStyle
- rename TextStyles.IDENTITY to TextStyles.ZERO
- rename TextStyleMode to TextStyleComponent
- fix a little Javadocs
Merge branch 'text-style'

* text-style:
  Fix up TextStyle - rename TextStyles.IDENTITY to TextStyles.ZERO - rename TextStyleMode to TextStyleComponent - fix a little Javadocs
  Implement TextStyle, add javadocs