moved traits dir inside classes dir
store field CSS classes in array, added Field::set_css_classes() to set multiple CSS classes using an array
added 'ig-cmf-input-color' default CSS class to all input color fields
added 'ig-cmf-template-CLASS_NAME' hook to allow override on template used to render a field UI
override template for input color field
added constant with version number value
added ig-custom-metaboxes-admin.js and enqueued it in wp-admin