HACKING.md: add profiling tips
common: add GetDurationString function to pretty-format duration.
mains: use GetDurationString function to show elapsed time.
Common: new function to pretty-print running time infomration
RunInfo: add variable to count units (Reads/pairs) processed.
lobSTR: pretty-print running time information.
lobSTR: print either "reads" or "pairs" in progress report.
Merge pull request #16 from agordon/minor_improvements

Minor improvements