New feature: Add optional sounds for killing sprees

[mindsolve]

For the player having a killing spree, play a Double Kill, Triple Kill and so on sound effect. Could probably be done with a resource pack?
Maybe also change the requirements (double/triple kill are with a 4.5s window, not 10s as in the plugin)

Links:

• Halo Kill Streaks: https://www.thegamer.com/halo-every-kill-streak-medal-guide-tips/#halo-combat-evolved
• Halo 1 Sound Effects: http://halo.bungie.org/misc/dialogue.html?cat=multiplay&orderby=name&page=1
• Force Resource Pack: https://github.com/SamB440/ForcePack

[mindsolve]

We could also use this to provide translations if we develop a custom resource pack