[ptx] nona and hugin

[Kevin]

Hi all,

	I tried out nona and it's a very impressive speedup.  A test stitch that
invovled 6 images was significantly faster.  Once feathering and color
correction is done this will be a large speedup for pano creations.
	
	I was wondering, have you put in a switch in hugin to select between
PTStitcher and nona?  I couldn't find one, but it'd be nice if there were
one so you can just select which on you wanted to use.

	Thanks again guys!
	Kevin