pep8: optimizations
phasemapper_core: numcore module for phasemapper
scripts: compatibility with new structure
reconstruction: new scripts

package: some minor corrections (mainly import statements), some old functions
         were revived (e.g. in MagData)

scripts: adaption to the new structure and sorting (more work is to do here...)

_version: __version__ string is now imported from this file

phasemapper_core.pyx: added to separate the corresponding numcore_functions
                      from kernel_core.pyx

Renames:
datacollection --> dataset
optimizer      --> reconstruction

scripts:
interactive_setup is now implemented in an extended Spyder startup file.
some other scripts are now
the rest is NOT adapted, yet, which is the next task at hand
furthermore scripts will be sorted and unused ones deleted in the next commit

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.