Changes to updateCells function

Added a new rule for deciding whether a cell should live or die.  This
rule comes from the game of life variation called high life.  The rule
is ‘If the cell is dead and has exactly 6 live neighbors the cell will
come alive’
added JMenu option for new rule to the game

The High Life variation of the game of life is new accessible through
the JMenu.  You can go back and forth between the original and the new
variation
Minor tweaks to the way I wrote this class

I got rid of the ‘’running’ variable because I already had that in the
Updater class.  It has no use in this class anymore.