Removed classes

Upon further thought, it seemed that these classes were both unnecessary
and unhelpful. Implementing these as reads would be the same things and
with fewer lines of code.
Working on functions needed for StoreSudoku
Minor changes
Introduced constraints and planning for next steps

Added functions needed to StoreSudoku
Added ElementConstraints to introduce constraints to each element
Merge remote-tracking branch 'origin/No-extra-data-classes'