Optimise custom map rendering

[barnabwhy]

• Remove floating point math from getDistance in org.bukkit.map.MapPallete
• Use bitwise & for bounds checks in obc.map.CraftMapCanvas to reduce comparisons Removed
• Reduce size of image being drawn in drawImage if it is larger than the available size.
• Use System.arraycopy to avoid iterating over the colors in the image.
• Swap x and y loops in CraftMapRenderer.render to be more cache-friendly

Saw a ~30% performance improvement in obc.map.CraftMapView.render()

Tested with a world containing many custom maps created using the ImageOnMap plugin, modified to remove this optimisation so that it renders every tick.
Before: https://spark.lucko.me/NVdWKmSlFr
After: https://spark.lucko.me/j6AJiFG9pD

[kennytv]

Thanks, I'll get to it some time in the following week(s)

[barnabwhy]

rebased