Thread leak - "Java Sound Manager"

Hello,

While debugging my own plugin, i added a command to monitor the threads used by bukkit and all the plugins.
I saw something strange in the output of the command, about 200 "java.util.Thread" called "Java Sound Manager".

So i did some tests with a vanilla server, a craftbukkit server without plugins and after i added all the plugins one by one.

Finally it seems that this kind of Thread is created by CommandBook.

Each time a player logged on the server, a Thread "Java Sound Manager" is created, but this thread is never destroy when the player logout. So after a few hours, depending on how many players you have on your server, you have a lot of useless threads still running :/

Like you said in your code comment in MidiJingleSequencer : " Sounds like utter crap" ^^

Tikkub

从 issue 中引用的 MidiJingleSequencer 代码开始，在装有 CommandBook 的 vanilla 服务器上监控玩家登录和登出期间的线程，以复现该行为。完成的标准是玩家登出后不再留下不断累积的 "Java Sound Manager" 线程。

由索引模型根据 Issue 内容生成。