added possibility to create derivative splines functors
added possibility to create derivative splines functors

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