function parseKernTable(data, start) {
    var p = new parse.Parser(data, start);
    var tableVersion = p.parseUShort();
    if (tableVersion === 0) {
        return parseWindowsKernTable(p);
    } else if (tableVersion === 1) {
        return parseMacKernTable(p);
    } else {
        throw new Error('Unsupported kern table version (' + tableVersion + ').');
    }
}
Loads a font from a URL. The callback throws an error message as the first parameter if it fails
and the font as an ArrayBuffer in the second parameter if it succeeds.
@param  {string} url - The URL of the font file.
@param  {Function} callback - The function to call when the font load completes