Further optimization of the new structure and 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