Widget refactor backward compat issues

[laundmo]

It seems my widget refactor had issues with backwards compatibility, specifically in a way that should have been compatible, and was recently reverted.

I'd like to ask the affected user to please share the widgets they were trying to use, and the errors they got, so i can fix this and add the new widgets system back.

- laund

[laundmo]

I've resolved one of the issues shared in https://groups.google.com/g/py4web/c/dfAehLbcqtg regarding FormStyle.widgets['fieldname'] = CustomWidget

https://github.com/web2py/py4web/pull/1001

[Massimo DiPierro]

I am going to review your PR asap, would be great if other users who use custom widgets could also test it with their code.

[Massimo DiPierro]

To people who use custom widgets. I would very much appreciate if you could try this changes and see if they break your code or not.