to discuss: remove old scan profiling

Scan profiling does a lot of memory allocations. It is not a problem per se, but now that we have yappi I don't think we should keep the old statistics.

Also, scan profiling is invasive in the code since we have to deal with it ourselves.

Scan.statistics is only useful if someone wants to look at statistics after a scan has been done: but, do we really use it ? Usually when a performance problem is suspected, the scan is run again with yappi.

So, I would recommend to remove it.

Linus made a great job with his profiling tool => I am more in favour of this initiative if we need something more elaborate.