After taking some time out due to a bust computer I am now back relearning the art of arduino and installing all of the necessary bits back onto the PC. What is weird is that I have installed the quadrature.h library which is linked from Jim's link2fs page. When I try and compile I get this:-

C:\Users\FS\Documents\Arduino\libraries\Quadrature/Quadrature.h:19:24: fatal error: WConstants.h: No such file or directory

compilation terminated

Any ideas?
Many thanks