Added Heart Item, Changed Hud and MAX_HP static int (read desc)

Added a heart item which adds a life if the player has less than 8 or
just replenishes current heart if at 8
Changed HUD so that it can accommodatethe adding and loss of hearts
Added a static int MAX_HP to the player class and updated all reference
that were 1000 to MAX_HP so that now, changing max hp will be just
changing this one int instead of the 1000 in various places