please use same terminology for TSSource and TSResourceSource arguments

TSSource has t0 and end whereas TSResourceSource has start_time and duration. It would be great if the interfaces for these two base classes were more similar. I'm not actually clear in fact why TSResourceSource doesn't just inherit from TSSource directly.

TSResourceSource also has a "start" function which creates the resource thread, which makes things even more confusing. I would prefer that both classes use start_time as their start time argument (instead of t0), and end_time and/or duration (not just plane end, which is confusing with start).