Make the refresh button on the Wiimote New plugin add new wiimotes in linux, instead...

Make the refresh button on the Wiimote New plugin add new wiimotes in linux, instead of disconnecting and reconnecting those that were already connected.  This makes it possible to connect new wiimotes during a game by openning the wiimote configuration dialog and refreshing.  You still need to tell dolphin that a new wiimote is connected using Ctrl+F5-F8 or the corresponding menu entries.

Also fixed a segmentation fault caused by the UDP Wiimote stuff when a thread was not properly ended.

git-svn-id: http://dolphin-emu.googlecode.com/svn/trunk@5847 8ced0084-cf51-0410-be5f-012b33b47a6e