Effects Demos: Fix typeErrors on puff and size demos
Menu: Adding a demo showing how to create category headers

Closes gh-1347
Datepicker: Fix currentText in Greek locale

Thanks Nikos Kalogridis

Fixes #10620
Closes gh-1349
Menu: Wrap menu items in a <div>

This avoids styling issues where ui-state-focus rules apply to submenus.

Fixes #10162
Fix: Various minor fixes
Autocomplete: Re-add wrappers to menu items