Added health bars for debugging.

For Debugging. Health bars can be customized.

The follow properties may be changed:
border size
bar size (affects height of health pips)
spacer width (affects distance between pips)
min pip width
set hp bar size relative to Entity size
use fixed width hp bar
use fixed sized pips (uses minPipWidth to determine size of pips)
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Added @Override annotations to Projectile and Item