Removed memory allocation failure warnings

glib calls abort() whenever a memory allocation fails, so this code was
useless. See http://www.gtk.org/api/2.6/glib/glib-Memory-Allocation.html
Update the info text if new images are found (either via --watch-directories or --lazy-load)

Furthermore, the region of the window where the info text is visible is
repainted. The region is estimated by the last known bounding box plus
some additional pixels to the right. This is a compromise to keep the
overhead low.

See bug #19.
Merge branch 'master' into depth_opt

Conflicts:
	README.markdown
	pqiv.c