added Canny detector
added Canny detector

capturePointer/vigra,mmuellner/vigra,DaveRichmond-/vigra,cbecker/vigra,xiwei-zhang/vigra,stuarteberg/vigra,kod3r/vigra,DaveRichmond-/vigra,ThomasWalter/vigra,stuarteberg/vigra,capturePointer/vigra,hmeine/vigra,cha007/vigra,dagophil/vigra,psteinb/vigra,capturePointer/vigra,funkey/vigra,mmuellner/vigra,stuarteberg/vigra,dstoe/vigra,martinsch/vigra,funkey/vigra,ThomasWalter/vigra,stuarteberg/vigra,martinsch/vigra,psteinb/vigra,timoMa/vigra,psteinb/vigra,ThomasWalter/vigra,capturePointer/vigra,mmuellner/vigra,stuarteberg/vigra,funkey/vigra,timoMa/vigra,mmuellner/vigra,xiwei-zhang/vigra,xiwei-zhang/vigra,funkey/vigra,ThomasWalter/vigra,hmeine/vigra,xiwei-zhang/vigra,psteinb/vigra,cbecker/vigra,funkey/vigra,kod3r/vigra,psteinb/vigra,kod3r/vigra,psteinb/vigra,hmeine/vigra,timoMa/vigra,cbecker/vigra,capturePointer/vigra,capturePointer/vigra,xiwei-zhang/vigra,hmeine/vigra,capturePointer/vigra,DaveRichmond-/vigra,mmuellner/vigra,timoMa/vigra,xiwei-zhang/vigra,dagophil/vigra,dagophil/vigra,timoMa/vigra,dagophil/vigra,DaveRichmond-/vigra,martinsch/vigra,martinsch/vigra,DaveRichmond-/vigra,dstoe/vigra,stuarteberg/vigra,dstoe/vigra,xiwei-zhang/vigra,kod3r/vigra,mmuellner/vigra,dstoe/vigra,psteinb/vigra,cha007/vigra,mmuellner/vigra,DaveRichmond-/vigra,cha007/vigra,DaveRichmond-/vigra,stuarteberg/vigra,ThomasWalter/vigra,cbecker/vigra,hmeine/vigra,dagophil/vigra,dstoe/vigra,funkey/vigra,cha007/vigra,hmeine/vigra,martinsch/vigra,cha007/vigra,hmeine/vigra,dagophil/vigra,kod3r/vigra,kod3r/vigra,ThomasWalter/vigra,dagophil/vigra,cbecker/vigra,timoMa/vigra,timoMa/vigra,dstoe/vigra,ThomasWalter/vigra,martinsch/vigra,cha007/vigra,cbecker/vigra,dstoe/vigra,funkey/vigra,kod3r/vigra,cha007/vigra