Rename twentyeleven_color_schemes hook to twentyeleven_enqueue_color_scheme,...

Rename twentyeleven_color_schemes hook to twentyeleven_enqueue_color_scheme, so its purpose is clear. Also rename twentyeleven_color_styles() to twentyeleven_enqueue_color_scheme(), and twentyeleven_link_color() (which sounds like a getter) to twentyeleven_print_link_color_style(). Some tidying in twentyeleven_layout_classes(). see #17198.

git-svn-id: https://core.svn.wordpress.org/trunk@17740 1a063a9b-81f0-0310-95a4-ce76da25c4cd