Convert extra "moveto" coordinates to "lineto" commands.

Per the [SVG spec](http://www.w3.org/TR/SVG11/paths.html#PathDataMovetoCommands):

> If a moveto is followed by multiple pairs of coordinates, the
> subsequent pairs are treated as implicit lineto commands. Hence,
> implicit lineto commands will be relative if the moveto is relative,
> and absolute if the moveto is absolute."
Add spec for multiple M/m coordinates being converted to L/l.
Merge pull request #1365 from rodovich/implicit-lineto

Convert extra "moveto" coordinates to implicit "lineto" commands