Enable or Disable 'All Visible' Addons

[….] Add another horizontal rule followed by two toggle buttons below it:
--- Enable All Visible
--- Disable All Visible

These functions will do exactly what they say. They will mass enable and disable all the addons visible. And by "visible" we mean the total addons from the libraries which are toggled on and visible on the screen. So if the only want to disable one group, they could just hide the others, click "Disable All Visible" then turn others back on.

Ref: Github Issue #18

https://github.com/jimpdx/perflight/issues/18