PyQt使用线程更新GUI

给几个参考文章：
http://stackoverflow.com/questions/9957195/updating-gui-elements-in-multithreaded-pyqt
http://stackoverflow.com/questions/2585442/sending-custom-pyqt-signals
http://stackoverflow.com/questions/14090353/sending-messages-between-two-widgets-using-signals-and-slots
http://themkbytes.blogspot.com/2012/06/pyqt-qthread-signal-gui-examples.html

Threading with PyQt4