Rewrite renderer

[tauraamui]

The rendering of the document has inconsistent colouring directives depending on whether a word is captured by a syntax segment, and affects whether certain parts of the lines are rendered in one instruction call, or as a full line of text. This is making it harder to implement aspects such as highlighting found search results for example. Additionally the view pane is unable to behave independently to the actual number of lines and position of the cursor etc.,

A refactor/overhaul of how we render is necessary at this point.