[API] Simplify type registration

https://github.com/nasa/openmct/pull/1302#discussion_r85417042

API.md

@@ -71,7 +71,7 @@ Custom types may be registered via
 [`openmct.types`]{@link module:openmct.MCT#types}:
 
 ```
-openmct.types.addType('my-type', new openmct.Type({
+openmct.types.addType('my-type', {
     label: "My Type",
     description: "This is a type that I added!",
     creatable: true

src/api/api.js

@@ -21,7 +21,6 @@
  *****************************************************************************/
 
 define([
-    './Type',
     './TimeConductor',
     './objects/ObjectAPI',
     './composition/CompositionAPI',
@@ -30,7 +29,6 @@ define([
     './ui/GestureAPI',
     './telemetry/TelemetryAPI'
 ], function (
-    Type,
     TimeConductor,
     ObjectAPI,
     CompositionAPI,
@@ -40,7 +38,6 @@ define([
     TelemetryAPI
 ) {
     return {
-        Type: Type,
         TimeConductor: TimeConductor,
         ObjectAPI: ObjectAPI,
         CompositionAPI: CompositionAPI,

src/api/types/Type.js

@@ -21,21 +21,12 @@
  *****************************************************************************/
 
 define(function () {
-    /**
-     * @typedef TypeDefinition
-     * @memberof module:openmct.Type~
-     * @property {Metadata} metadata displayable metadata about this type
-     * @property {function (object)} [initialize] a function which initializes
-     *           the model for new domain objects of this type
-     * @property {boolean} [creatable] true if users should be allowed to
-     *           create this type (default: false)
-     */
 
     /**
      * A Type describes a kind of domain object that may appear or be
      * created within Open MCT.
      *
-     * @param {module:opemct.Type~TypeDefinition} definition
+     * @param {module:opemct.TypeRegistry~TypeDefinition} definition
      * @class Type
      * @memberof module:openmct
      */

src/api/types/TypeRegistry.js

@@ -20,7 +20,18 @@
  * at runtime from the About dialog for additional information.
  *****************************************************************************/
 
-define([], function () {
+define(['./Type'], function (Type) {
+    /**
+     * @typedef TypeDefinition
+     * @memberof module:openmct.TypeRegistry~
+     * @property {string} label the name for this type of object
+     * @property {string} description a longer-form description of this type
+     * @property {function (object)} [initialize] a function which initializes
+     *           the model for new domain objects of this type
+     * @property {boolean} [creatable] true if users should be allowed to
+     *           create this type (default: false)
+     * @property {string} [cssclass] the CSS class to apply for icons
+     */
 
     /**
      * A TypeRegistry maintains the definitions for different types
@@ -40,8 +51,8 @@ define([], function () {
      * @method addType
      * @memberof module:openmct.TypeRegistry#
      */
-    TypeRegistry.prototype.addType = function (typeKey, type) {
-        this.types[typeKey] = type;
+    TypeRegistry.prototype.addType = function (typeKey, typeDef) {
+        this.types[typeKey] = new Type(typeDef);
     };
 
     /**