Sieve class

A class named sieve and iterator were made to match the implementation of primesieve.org to use in ntheory functions.
Using the L1 data cache size, the time for 1e8 using our implementation goes down to 0.36s. It's about 25% faster than just using the code from the above link. 
I'll commit as soon as I find a way to find the L1 cache size. Do you know of any way?