Re-added accessors for sake of unit test
Added CellIndex struct (and init test), to be used for index arithmetic and array subscripting.
Corrected CellIndex constructor.
Cell linking now handled with CellIndex. Overloaded subtraction operators for CellIndex. Added negative initialisation case to constructor.
Added cell spawning in scroll direction. Loops forever unless direction is forwards as centre is measured relative to that corner.
Added unlinkCells function. Removed unecessary index wrapping from linkCells function.
Corrected unlinkCells name typo.
CellIndex can now be created fromAngle.
cells can now be destroyed and unlinked.
CellMapp now deletes as it scrolls.
Refactored CellIndex to perform same range check on all operators. Previously neglected case of negative value arithmetic.
CellIndex checks range with while loops, not modulo.