get shape parameters from manually set positions

[dbuezas]

For some applications it would be very useful to allow for manual corrections of the face feature positions and to get the matching face model parameters from them. This would allow more precise face classification, which is what I am working on. The library can already do that from the patches positions, but I'm having troubles hacking the overridden positions there.

My approach is to override vecposvector in the line 505 so that it represents the manually set position and then let the parameters converge. Does it sound like it might work or am I completely out of track?

I would also like to disable the shape constraint since the input data is human curated but I got lost there.

Thanks!