Don't specify type in the key for type, rely on the value

Rather than appending -a to the type, we should be able to check
what we need in the value
Use the wsublock-type key to determine if a section is POSTed

This allows us to treat a few different kinds of data in the same
way and removes some of the complexity. It also starts treating
the type input as an actual type
Account for the 'halves' class in get_section_class
Remove misleading use of $classes in meta box output
Complete initial support for sideleft and halves admin layouts
Consolidate the intitiation of tinyMCE editor blocks