Changed variables to attributes from calculateOddPrimes()
I want to make the code more intelligible by making more methods and
this requires giving all methods access to these moved attributes.
Split method calculateOddPrimes into 2, created getNextPrime()
calculateOddPrimes was a messy method, needed to split up the code
to make it more intelligible, also did some format correcting in this
commit.
Encapsulate code into updateNextSquaredPrime method
This code is unclear and I felt that it needed to be hidden away to make
code readability better and therefore created a method for it.