[Alan] Modify sieve.alan (change size of primes array)

[harrisp28]

Change size of primes array from 100 to 101 so primes[0] and primes[100] elements can be accessed (otherwise change code so we are not accessing them).

[kostis]

Thanks for the PR and for noticing this inconsistency. I think that the code is still inconsistent because, when size us declared as 101, the array[100] entry is not initialized in the first while loop.

I would rather prefer a PR that makes sure all accesses to the primes[] array are consistent and within the [0,(n-1)] interval (i.e., that we never access the primes[n] entry). In other words, perhaps it's better to change the while loops on lines 33 and 43 to also use strict inequalities. Put it differently, I do not like that the conditions of the while loops are not uniform, currently.

[kostis]

Looks good - thanks