Implement heapsort and quicksort in Go and Python
Add README
Run Go and Python tests with a single test script
Add profiling script and sample results
Update README.md
Clarify comment for profile output format string
Add analysis of profiling data
Make error messages consistent between languages
Don't throw error given zero input

It's better to simply do nothing in such cases, which is more
consistent with Unix sort behavior and the Unix philosophy overall
Clarify explanation of overhead in analysis