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.
Yes, if the starting border is an option, then we should provide it. From the javadoc description and naming of variables, I couldn't presume that the function was provided by vanilla Minecraft.

If possible, please rename as suggested, and further emphasize the javadocs in both this method and the above setDiameter method to note that the latter takes the current world border whereas the former takes the given radius.