Version 0.7.2: 2007-09-06
  * Replace special characters <>&'" by their XML entity (&lt; etc.)
    in setSVGShapeToolTip() (and add extra arg sub.special=TRUE to
    this function to allow inhibiting this substitution).  Do the
    same for the label in text().
Version 0.7.1: 2007-06-12
  * small change to SVG code to make it display tips in more browsers
  * added options to control font size and opacity in tips
Version 0.7.0: 2007-04-30
  * based on RSvgDevice version 0.6.1 by T Jake Luciani <jakeluciani@yahoo.com>
  * supports line types (dotted, dashed, etc.)
  * supports one and two line tool tips
  * supports hyperlinks on shapes
  * fixes a potential buffer overflow problem in the C code
