Control of Gathered Statistics

The user should be able to designate the level of gathered performance statistics as it is likely that detailed collections will have a performance impact (perhaps not?).

A new configuration parameter should be introduced – perhaps named DIAGNOSTIC_LEVEL – that controls the level of detail gathered:

0 – the default, gathers general system level performance data and general session information. Basically mirrors what is in version 5.0 with SHOW commands.
1 – gathers all system level performance data including system and session wait information
2 – gathers all system level performance data including system and session wait and I/O information
3 – most comprehensive: gathers all system and session level performance data, including performance diagnostics at the object level