Factored out filename creation.
Re-factored #to_text
Re-factored.

Removed debug text from #from_ankh_file
Changed #cell_at to only take a GridPoint.
Heavily re-factored.

initial_highlight -> #initial_state, sets more up now
highlight_word and #highlight_current -> #highlight
Added #current_word which gets the positionss for the current word cells.