Override default params for plugins

This is a feature request idea, but will likely just happen with Gadgets

Say the default param for a plugin is X but on my instance, I prefer Y

As of Tiki8, I need to go an edit the code in lib/wiki-plugins/* or to make a plugin alias

This would be nice as a pref, and thus, could be part of System Configuration

This could also permit use to get rid of the 100+ quasi useless inline prefs like wikiplugininline_addfreetag We should be able to set prefs per Tiki site, and override for each usage.