Support for non-standard runtime multi items.

[davetcc]

This issue is mainly in the designer and API/embedCONTROL UIs, but a little work is needed on the library side.

I would imagine this falls into two categories:

• Support for text items that just have a different filter/validation requirement. For example email address.
• Support for completely custom editing capabilities such as serial number, phone number, or another such editable field that may not be based on char.

Further to this, these items would need to be both viewable and editable within embedCONTROL and the API, this needs a bit more thought, around how to provide the custom editing capability.