HaikuDepot: Fixed spelling of ascent and descent nouns
HaikuDepot: Work-in-progress on a TextDocument class.

 * This is mostly still targeted at the use-case of parsing
   some mark up text and building a static representation
   of the styled document which can be layouted and rendered.
 * Lots of TODOs and almost nothing is tested.
HaikuDepot: Paragraph: Added Length() method.
HaikuDepot: Fix passing back cloned StyleData objects

 * In the methods that create a new style data object
   by cloning the object and changing the respective
   property, returning a Reference to a style data
   object makes it easier on the calling side to deal
   with the same object being returned or a new one.
HaikuDepot: Redesign TextStyle as CharacterStyle ...

 ... following the example set by ParagraphStyle and
 ParagraphStyleData.
HaikuDepot: Re-implemented TextLayout as ParagraphLayout

 * Completely unfininished and untested, won't even compile,
   but is not included in the build. The idea being to wrap TextSpan
   objects and split them onto Lines each containing their own
   layouted TextSpan chunks. TextLayout will later be repurposed
   to off-load the layout of individual text paragraphs to
   ParagraphLayouts.