profiling: move profiling code from dispatch.py (API) Currently, profiling code lives in dispatch.py, which is a low-level module centered around command dispatch. Furthermore, dispatch.py imports a lot of other modules, meaning that importing dispatch.py to get at profiling functionality would often result in a module import cycle. Profiling is a generic activity. It shouldn't be limited to command dispatch. This patch moves profiling code from dispatch.py to the new profiling.py. The low-level "run a profiler against a function" functions have been moved verbatim. The code for determining how to invoke the profiler has been extracted to its own function. I decided to create a new module rather than stick this code elsewhere (such as util.py) because util.py is already quite large. And, I foresee this file growing larger once Facebook's profiling enhancements get added to it.