Specify stack size in Thread class

Hi,

the default stack size of threads created with the Thread class (512kb on osx) is to small for some of my purposes. For now, I have altered the class with an optional call to pthread_attr_setstacksize as a workaround. Would it be possible to add support for that in the library?

Thanks a lot!

Thanks for the suggestion. I've added this to the constructor of JUCE thread on the latets tip.