Reworked init of d2o.
Implemented a distributor cache.

Implemented interface for slicing methods in slicing distributors. fftw_distributor is now a special case.
Implemented flatten routines for d2o.

Fixed a small error in random number generation in nifty_lm.py

Finished operator and diagonal_operator.

Added direct_dot to nifty_simple_math.py.
Begun with direct probing implementation.

Updated nifty_core.field to really delegate everything to its underlying space. The methods pseudo_dot and tensor_dot are not fixed yet.

Misc changes. Separation of field and space functionalities further improved. The fft of a field now runs purely with a distributed data object as it is now the natural data object of rg_space.

Added a mpi_dummy.py. Integrated the paradicts to the spaces. Implemented unary_operation, binary_operation and norm in the spaces. Extended the functions of the distributed_data_object for the unary and binary operations.

Updated README and nifty_core __version__

fixed the healpix import test

regression keyword removed

lm __init__.py Added check for healpy version