Format logs without sip.voidpointer

Most messages in the log contain a piece of text "<sip.voidpointer
object at hex-address>". This is the result of
str(QtCore.QThread.currentThreadId()) but the thread is typically main
because this runs under a proxy to main function and it adds no value
and makes the text less readable.

This fix removes this string if it starts with sip.voidpointer.