Initial commit of denoising module
Renamed module denoising to denoise, added init files and a usage example
Ported all c++ code to Cython.
Added an S0 denoising example.
Renamed ornlm_module.pyx to ornlm.pyx (there was a naming conflict with the c++ source code, but it was already eliminated)
Style corrections to comply with PEP8. Added documentation to exported functions from ornlm.
Added Addaptive Optimized Non-local Means filter with Rician correction (by Pierrick et al.).
Started changing coding style in files and moving files in their correct position according to the dipy guidelines