Add missing entity effects. Adds BUKKIT-3311

There are many effects that were not present in the API prior to
this commit. These effects are being used by the implementation,
but cannot be accessed via plugins.

This commit exposes these effects using the EntityEffects enum,
allowing for plugin authors to make use of these effects. However,
many of the effects require certain conditions to be met before
they will be visible to the client, much like some of the existing
effects.
Account for spacing in MapFont#getWidth(). Fixes BUKKIT-4089

Prior to this commit MapFont#getWidth() did not account for the 1px
spacing inserted by CraftMapCanvas#drawText().

This commit adds the consideration of the 1px spacing per character
while taking care to not consider the last character as it will not
have a 1px space behind it. This commit also ensures the method will
not check a 0-length String.