Added a deform option to the multi-layer-mosaic method.

Added a deform option to the multi-layer-mosaic method.
Instead of transforming each tile with the affine (rigid or
whatever) transformation estimated in the global
intra-and-cross-layer optimization, the center-points of each
tile are used to deform the intra-section registered layer with a
MLS-transform.  That is, the overall appearance of the registration
is that of the globally optimized but sections are continuous in
themselves.

TODO Lacking a sufficient data set, not yet really tested.  I will
soon try it with the L1 "second_set"...