Plugins VAMClock

Minor code revision needed as the additional plugin security measures in this version prevented correct operation.

For VAM v1.20.0.9 and above the requirement for the "SessionPluginBooter" script to be attached to an "Empty" atom in the "scenes/default. json" is no longer necessary for this plugin to load at VAM startup.
See the note in the new "Session Plugin Presets" tab on how to set persistent session plugin presets.