make 'id' required
update docs
update plugin schema
update the workbench to support change notification
remove validation from api - it will be handled differently
update schema to allow an extension point to specify an interface class
expose the 'schema' and 'interface' properties on the ExtensionPoint
validate the extension object against the specified interface
reorder id and point
update core plugin spec
remove dead files
move some stuff around
remove CorePlugin from api file