svglite 1.0.0

svglite is fully featured svg graphics device that works on all platforms, forked from RSvgDevice. It supports all graphics device features:

• All types of line dashing are supported (#15). All line end and line join
  styles are supported (#24).
• Text is now coloured, and uses the same default fonts as R (Arial,
  Times New Roman, and Courier). Font metrics are computed using the
  gdtools package so that plotmath() and strwidth() now work.
• Transparent colours are now generated with rgba() rather than using
  stroke-opacity and fill-opacity styles (#16). NA fills and colours are
  translated to "none".
• par(bg) affects the background colour (#8).
• Rasters are supported by embedding base64-encoded pngs in a data url (#2).
• polypath() is now supported, which also allows the showtext package to
  render fonts correctly with this device (#36).

We also made a few other tweaks to the rendered SVG:

• Only the viewBox attribute of <svg> is set (not width and height):
  I'm reasonably certain this makes it easier to use in more places (#12).
• Default styling properties are specified in a global <style> element:
  this reduces overall file size, and should make it easier to re-style
  the output for your own needs.
• You can now only produce a single page per device - previously this worked
  but produced incorrect output (#5).
• Output no longer contains dummy <desc> element (#4)

And added some helper functions:

• xmlSVG() and htmlSVG() make it easier to view generated SVG, either as
  raw XML or in RStudio/the browser.
• editSVG() opens the SVG in the default SVG viewer/editor.