Build error for residuals with scalar output

[trfabian]

Defining filters which contain residuals with scalar output leads to a conversion error for the jacobian arguments of the residual's JacPre, JacCur and AddNoise methods.

[bloesch]

thanks for the note. this is related to a different striding for row-vectors. I believe that this should be solved by simplifying the Jacobian interface: instead of passing a block matrix, passing the full matrix may be a solution...