Added a firework death message option.

Config version updated to 33!
Regenerate your configuration files where possible.
If you don't want to regenerate, here's a change list:
- All instances of %weapon_name% in default death messages were changed to %weapon%.
- All "...was finished off..." default death messages were removed.
- Added FallKillWeapon, FallFinishKill, FallFinishKillWeapon death message settings below the FallKill one. ( these messages are not implemented yet)
- Added a Firework death message setting above the Elytra one.
- The default EnderDragonBreath message was changed from "%plrtag% was killed by Ender Dragon using magic" to "%plrtag% roasted in dragon breath" to reflect intended vanilla message.