Fixed bug in createflowpaths where connected roof pixels that lack nearby
impervious surfaces would have an incomplete flow table, with some receivers
having accumulated areas of NaN.  Now if a nearby impervious surface cannot be
found for a roof, connected flow is routed to the nearest stream pixel.
Merge branch 'master' into develop

Conflicts:
	cf/include/route_roofs.h
	cf/src/compute_connected.c
	cf/src/main.c
	cf/src/route_roofs.c