String UrlEncode(String s)
{
	const char *p = s, *e = s.End();
	String out;
	for(; p < e; p++)
	{
		const char *b = p;
		while(p < e && (byte)*p > ' ' && (byte)*p < 127
			&& (IsAlNum(*p) || *p == ',' || *p == '.' || *p == '-' || *p == '_'))
			p++;
		if(p > b)
			out.Cat(b, int(p - b));
		if(p >= e)
			break;
		if(*p == ' ')
			out << '+';
		else
			out << '%' << hex_digits[(*p >> 4) & 15] << hex_digits[*p & 15];
	}
	return out;
}