Added pure ruby svg outputter.
Added pure ruby svg outputter.

Registers to_svg, a pure ruby rendering of 1D and 2D Barby barcodes into SVG.

Also registers bars_to_rects and bars_to_path, which create SVG representations
of the bars, allowing this output to then be merged into another existing SVG
wrapper.

Standard size and margin options supported, as well as opts[:rot] for rotating
bar codes 90 degrees.

Signed-off-by: Tore Darell <08a3738bfad74528eb123988a40c33b2483e473a@gmail.com>
bring/barby,cainmodyo/barby,modyo/barby,heliocola/barby,yob/barby,suman5040/barby,toretore/barby