WorldBorder and Potions

Added new method to set the startingDiameter, endDiameter and the time it will take [void setDiameter(double startDiameter, double endDiameter, long time);]
Added Splash potion option.
Changed Radius to Diameter.
Changed get/setBlockBuffer to get/setBuffer and changed the return and parameter to double as it is not measured in whole blocks.
With both of these Splash is specified in Minecrafts PotionEffect. Also if you have splash in ItemStack your bound to have people try and set a normal item to a splash potion. Also if you have a potioneffect already made, how are you supposed to change it in the implementation?