Implementation of private methods

In current implementation of widgets it's easy to accidentally overload an internal methods.

For example, I can create an own _createButtons() method in my widget inherited from $.ui.dialog. As a result I will corrupt internal routines in $.ui.dialog widget.

I suggest to implement a real private methods to avoid possible conflicts.
For simplicity reasons I suggest to expand naming conventions. Like in python or glibc all methods started with two underscore symbols will be treated as a private methods.
To call a private method you will have to use a special call similar to _super.