Allow ''expand/collapse all'' feature for datasources

It would be useful to have an option to \'\'expand/collapse all\'\' graph nodes for a datasource at the datasource, host, and group levels. It would even more helpful if this setting could be saved/stored per user per datasource level.

For example, when Fred clicks on his \'\'Bedrock Quarry Database Servers\'\' group, that the \'\'CPU cores- (WinCPUCore-) datasource graphs would automatically be expanded for all servers and all CPUs. This is the \'\'default\'\' view he wants to see every time he clicks on the \'\'Bedrock Quarry Database Servers\'\' group.

Barney, however, is interested in seeing the \'\'Memory and Processes (WinOS)\'\' graphs for the Bedrock Quarry Exchange Server (\'\'Dino\'\'). Each time he clicks on \'\'Dino\'\', he\'d love for the graphs to be automatically expanded.