[Speed] perf 0.7.3 released

The Python perf module is a toolkit to write, run, analyze and modify benchmarks: http://perf.readthedocs.io/en/latest/

Version 0.7.3 (2016-08-17):

• add a new slowest command
• convert: add --extract-metadata=NAME
• add --tracemalloc option: use the tracemalloc module to track Python memory allocation and get the peak of memory usage in metadata (tracemalloc_peak)
• add --track-memory option: run a thread reading the memory usage every millisecond and store the peak as mem_peak metadata
• compare_to: add --group-by-speed (-G) and --min-speed options
• metadata: add runnable_threads
• Fix issues on ppc64le Power8

Victor