html.streams: the 'image' character stream style now generates an <img> HTML element

html.streams: the 'image' character stream style now generates an <img> HTML element

NOTE: You must manually copy your image resources to your web server
      such that the images are available from the "/images" root URL.
	  For example, if your resource is "vocab:definitions/icons/normal-word.tiff"
	  then it should be copied such that it is available via the following URL:
	  "http://myserver.org/images/basis/definitions/icon/normal-word.tiff"
	  (the original path is first normalized and then the Factor root prefix
	   is stripped away).

NOTE: Factor's definition-icons are in TIFF format, which appears to be
	  supported out-of-the-box by very few web browsers (namely Safari).
	  Perhaps we should switch from TIFF to GIF or PNG? Are these vocabs
	  ready to be used?