Primal-dual algorithm

This is an implementation of primal-dual algorithm, based on the C++
source code by Vadim Pisarevsky. It was extended to handle the denoising
based on multiple observations. It also contains documentation and
tests.
Started working on primal-dual

So far it does not even compile.

Addition to prev

Just forgot to add two files.

Integrated one-observation primal-dual into optim

What we have now is the code (written by Vadim Pisarevsky) that can
denoise the image based on one observation and some tests, based on
lena.jpg.

Catching the bug in denoiser

This revision won't compile or will give you a runtime-error/crash. It
is kept only for historical purpose. I'm catching a bug

Bug is fixed

Looks like now the algorithm is coded properly. If this is really so, it
is time for regression tests, code cleaning and documentation.

Test for multiple-observation primal-dual

It remains to:
    1) Make sure that the algorithm is coded correctly
    2) Optimize the code
    3) Clean the code
    4) Write better tests, if desirable
    5) Write the documentation

Started writing documentation for primal-dual

It is incomplete, so far.

Started working on documentation for primal-dual

It remains to add some mathematical justifications.

Finished writing documentation for primal-dual

Not perfect at the moment, but legible.