export tree.json file listing modules in details.xml
output nested classes into details.xml

ex: `<object location="dijit/Tree.Tree">`
make tree.js contain a module's nested classes
Generate tree from dojov1.js.

Because tree.js needs to list the exact set of objects that dojov1.js wrote into details.xml.
extension=true flag for third party properties.

Set extension=true on any properties that come from modules that the user needs to manually require, ex how LayoutWidget.js adds properties to _WidgetBase.

Refs #52, but doesn't fix the problem where only some of the third-party properties are showing up and others arent't.
export tags
Rename extension to extension-module.

"Extension" is already used by widgets to indicate that certain functions are especially meant to
be changed by the user.
give nested objects their own pages too
Make id's unique when module and directory share name.

For example, dojo/date is both a directory, and the MID of dojo/date.js.
So, giving the directory (aka folder) the id of "dojo/date/".