Added code to keep children of combo boxes and lists selected when the ...

...parent changes selection. Original selection of the ListItem is retained in the list sent to the client browser and then applied when child list is redrawn.
Selection of an item is preserved as 0 or 1 being the first character after the separator between ID and a text of an item.
Additionally I'm adding jquery.d.ts to the main MvcForms folder as without it it wouldn't compile in the main folder - I suspect that you have it in your folder, but not in GIT?