Removed widgets, Font, Gen popup impl #21, BG styling

* Removed "old" widgets that have become deprecated
* Added awesome font
* Removed sidebar icon
* Select optiontype now supports both associative arrays, as well as
plain "sets" (use associative one to distinct value from texts
("value"=>"translation", "value2" => "translation 2")
* Colorzen optiontype and sheet have properties to show/hide color sets.
By default all are turned on ("colorset_flat_enabled"="false",
colorset_lightgradient_enabled="false" and
"colorset_mediumgradient_enabled="false")
* Shortcode rendering of placeholders now loads metadata and stored it
in nxs_global_placeholder_render_statebag.
* Shortcode rendering handles rendering background styles in such a way
that background colors are applied for the height of the widget, not
just the content that "contains" information.