Fixed Issue with large XP rewards
Fixed Issue with large XP rewards

- Updated LevelUp function to check if another levelUp is necessary and
recurse if so. This is for situations where player may get more than one
levels-worth of XP. For example, a boss fight.
- Added more robust comment to XP bar width calculation to hopefully
explain the math slightly better.

geneldodge/CubeClicker,geneldodge/CubeClicker