Auto-adjust MaxScale parameters according to server settings

Some MaxScale parameters depend upon server parameters in such a way that if a MaxScale parameter is configured without any regard to the server parameters(s) on which it depends, then MaxScale may not function properly.

For instance, the persistmaxtime specifies how long a connection can stay in the pool before it is discarded. However, it makes no sense with the value of persistmaxtime being larger than wait_timeout of the server. The former should always be smaller than the latter.

MaxScale should sniff the server parameters and, if necessary, adjust any MaxScale parameters that are in conflict with the server ones. For some cases it should be possible to specify that the MaxScale parameter is directly derived from a particular server parameter.

The sniffing should be performed at regular intervals, so that any changes made at runtime to the server parameters are automatically taken into account.