fixed const correctness of Kernel2D
fixed const correctness of Kernel2D

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