Grunt file : remove phpcs
customizer panels => remove useless check if wp version >= 4.0
new private property : is_wp_version_before_4_0
Fix Customizer frozen bug. case default control : fallsback to no input attr if wp version < 4.0
because input_attrs() was introduced in 4.0
customizer sections for wp<4.0 : set conditional priorities ( based on is_wp_version_before_4_0) to reoder the section more consistently
skin, header, content, footer....