function isSpace(i) {
    return ((glyphs[i].name && glyphs[i].name === 'space') ||
      (txt.length === glyphs.length && txt[i] === ' ') ||
      (glyphs[i].index && glyphs[i].index === 3));
  }
Returns an opentype path for the supplied string and position.

@param  {String} line     a line of text
@param  {Number} x        x-position
@param  {Number} y        y-position
@param  {Object} options opentype options (optional)
@return {Object}     the opentype path