Hello!

I started using the Ticker frontend of Newsticker and didn't like that
it continuously scrolls the echo area.

I am submitting the below patch, which only displays the list of items
once, at `newsticker-ticker-period` intervals. The default behavior has
not changed. Not sure if this warrants a change in NEWS.

Thanks!

	Newsticker ticker scrolling options to only display periodically

	* lisp/net/newst-ticker.el (newsticker-ticker-period): 
	Scroll news items only once each period.

	* doc/misc/newsticker.texi (Frontends):
	Document ticker scolling behavior.