#1 adding the ability to choose the worker_thread

[Benoit Hamet]

it could be good to be able to choose the m_thread type in the worker_thread :
As first idea coming in mind: for some mathematical library, we need to deallocate memory per thread, and doing so in the real worker thread is a real need (simply overloading the thread destructor).

With the current system, we must put "clean memory" small function to schedule and hope that all threads will be call with them ... wich is really random.

Regards.

Benoît.