[cv6] Core RC 3 1.2.0

Core AddOn which from now on, (nearly) all my AddOns will require.


Besides Icon handling and Assset Upload some other minor thing that I share between my AddOns.
Mostly this is related to Font Awesome handling. See Edit Option Group as Demo.
Also see pictures whats inside.
New Resource Icon like this resource has, means, it needs this Core Addon.
Contains:


Template for FontAwesome Icon Chooser with menu
Template for Asset Upload incl. preview
Templates to use both functions in options and style
Templates and a trait for creating a tabbed index
.less functionality to use the FA Icon in .less files
some related style and options
central opacity setting (at least for all cv6 AddOns)
Setup Traits
js Dependency handler