Revert "Revert "jQuery.widget: Documenting 1.11's instance method for all widgets.""

This reverts commit cd2e4fbe6e282f9957e2e2b4f13996190e83f211.
Revert "Revert "jQuery.widget: Document that instance can be called on any element to determine whether it is a widget.  Fixes #77.""

This reverts commit 404a476727ed1b81ec791a53a107b712c9002317.
Dialog: Remove array and string notations for position option.
Selectmenu: added Selectmenu entry. Fixes #67
Selectmenu: fixed wrong position option description
Selectmenu: add inline CSS for examples
Selectmenu: alphabetical ordering of events, options, methods
Selectmenu: adjust documentation to latest changes
Selectmenu: Coding standards and spelling fixes.
Selectmenu: Editing pass.

Changed the description to be consistent with other widgets. Small grammatical changes here and there.
Menu: Menu items no longer require <a> tags.
Spinner: Document isValid() method.