Notes on text widget:

added the following options to configure:

	-height			requested height of the widget (in lines)
	-scrollhcommand		updates horizontal scrollbar
	-scrollvcommand		updates vertical scrollbar
	-wrapmode		one of none, char, word or fixed.
				fixed means wrap on characters based on the
				user supplied width even if the width of the
				window changes.

added following widget commands:

	viewline		takes a lines number as argument.
				positions line at the top of the window.
	edit			takes a variety of editing commands.
				(incomplete)

other changes:

	the @ option for mapping the pointer to a text position takes both
	x and y coordinates as @x,y

known problems:

	there is one case where word wrapping doesn't work exactly right.

	could reclaim some memory when lines are shortened.

	the cursor isn't always on the right line.

	selecting to the bottom of the window will pick up the next line.