Correct "exception-safe" insertion.
Correct "exception-safe" insertion.

	* src/NDesk.Options/NDesk.Options/Options.cs: Properly keep track of
	  the names that were added to the Dictionary, so that if an insertion
	  fails we can properly "roll back" to the previous state.

chakrit/ndesk-options-mirror,MikeJansen/NDesk.Options.StrongNamed,MikeJansen/NDesk.Options.StrongNamed,MikeJansen/NDesk.Options.StrongNamed,chakrit/ndesk-options-mirror