not represent the correct matrizes (hopefully, now they do).

>>> PACKAGE
forwardmodel, kernel, phasemapper:
        b_0 is now again inherent part of the kernel.
projector:
        Corrected .jac_T_dot, now delivers product for the correct matrix.
>>> SCRIPTS
simple_reconstruction:
        Does simple compliance tests for 1 and 2 projections and tests a simple
        solver via scipy.sparse.linalg.cg for the reconstruction.

documentation: minor changes and updates of docstrings

modularity and compatibility with future algorithms and ideas.