[Gzz] 10th, 11th (Tjl)

[Tuomas Lukka]

10th: very little work, mostly a holiday.
11th: blobs:
        1) finished mesh class
        2) worked out the invariants of surface->surface mapping.
           After the fact, it's of course trivial: draw an infinitesimal
           circle and the invariants are the principal axes' lengths of the
           ellipse you get when the rubber is stretched.
           However, getting to that took quite a while of thinking
           and linear algebra...
        3) Implemented previous, seems to work (at least is invariant
           w.r.t. performing same operations to source and target vectors.
                
           The invariants I'm now thinking of using are t*u and (t^2+u^2) / 
(t*u),
           i.e. the Jacobian determinant (area change) and a sort of
           measure of the skewness.

This means that I'm finally getting close to making the final program
for blobs and getting back to gzz proper.

        Tuomas