thaw-colorer in color:text<%>

Start coloring a frozen buffer again.

• (send a-color:text thaw-colorer recolor retokenize) -> void
     recolor = #t : boolean
     retokenize = #f : boolean

  If recolor? is #t, the text is re-colored. If it is #f the text is not recolored. When recolor? is #t, retokenize? controls how the text is recolored. #f causes the text to be entirely re-colored before thaw-colorer returns using the existing tokenization. #t causes the entire text to be retokenized and recolored from scratch. This will happen in the background after the call to thaw-colorer returns.