Plugin Manager – switch groups of plugins on/off

Have an ability to switch groups of plugins on and off.

Examples of how a user might want to use this feature.
a) use a group of plugins for a “diagnosis mode”
b) testing a range of plugins on the live site, to do side by side comparison, but turn them all off afterwards.
c) run the site at different levels of complexity, so make groups for “bare bones”, “essential”, “equipped”, “full bells and whistles”. This is what might be used for working around some problem that has arisen. So cut back the features so the site still works, but then fault trace from there.