Handle 'delete' and 'backspace' slightly differently for purposes of 'undo'

Original nano commit: 4944
http://svn.savannah.gnu.org/viewvc?view=rev&root=nano&revision=4944
Original nano commit message:
	Differentiating between undoing a Delete and undoing a Backspace -- the
	cursor should be in a slightly but significantly different position.
	Patch by Mark Majeres.
Change line-wrapping to use existing line-break code

Original nano commit: 4945
http://svn.savannah.gnu.org/viewvc?view=rev&root=nano&revision=4945
Original nano commit message:
	Rewriting the line-wrapping code to make use of the existing line-break code.
	And undoing line wraps together with their causal text additions, and not as
	separate actions because the user did not make them.
	Patch by Mark Majeres.