Item7896: site statistics to be made easier to test and debug, not affecting web stats

The statistics script generates the site-wide statistics in addition to stats of webs. Running the statistics script from command line or cron to generate site stats and web stats has the following issues.

1. If site stats generation fails, it's difficult to figure out where exactly.
2. If site stats generation causes a fatal error and the statistics script aborts, web stats are not made at all. It's because the site stats is made before web stats.
3. There is no way to generate the site statistics without generating web stats.

To cope with the above, the following measures will be taken.

1. During site stats generation, more progress reports are made.
   1. The numbers of topics and attachments of each web are counted. Before each count, the name of the web is printed.
   2. The fact that file size summation is underway is printed.
2. Site stats is generated after web stats unless otherwise explicitly specified.
3. The "site" pseudo web is used to specify to generate the site stats with the webs parameter. Together with the previous point, if the statistics script runs from command line without the webs parameter, it's as if all webs are specified plus the "site" pseudo web at the end of the list.

-- TWiki:Main/HideyoImazu - 2020-05-26