void offer(char b) {
            data[start] = b;
            start = (start + 1)%size;
            count++;
        }
Date 03/26/2016
@author Tushar Roy

Given a reader which only reads 4 bytes implement a Reader which can read bytes of give size.

Reference
Read N Characters Given Read4 II
https://leetcode.com/problems/read-n-characters-given-read4-ii-call-multiple-times/
src/com/interview/misc/Read4Function.java