improve how properties split into sections

[wkeese]

Although we now have separate pages for major objects exported from a module (ex: dijit/Tree.TreeNode), it's still confusing how the main module page is laid out:

• constructors are appearing in the "methods" section
• (relatedly) prototype properties and normal properties are mixed together

Probably there should be a separate section for normal properties, or at least normal properties that have their own pages.