0.2-16 Added text to help page for tri2nb() to show ways of triangulating 
	on a grid; added nb2blocknb to fill out an nb object with spatial
	"replications" that have to neighbour each other; poly2nb() altered
	to use the pythag() C function internally, rather than creating several 	large matrices - this should alleviate memory problems.

0.2-14 Dependency on R-1.9.0 because findInterval() in R altered to help 
	with map class interval finding, making a modified local copy
	superfluous.

earlier briefly:

because spdep depends on the maptools package, it must be present for 
	spdep to load correctly.

all after 0.2-5: error in errorsarlm() and lagsarlm() corrected - 
	the error was the silent assumption that all lagged intercepts
	followed "W" style weights, not the actual weights being used.

