Added the 'MP05' R2eff calculating function to the relax library.
This is the Miloushev and Palmer 2005 R1rho analytic model for 2-site off-resonance exchange.
This follows the tutorial for adding relaxation dispersion models at:
http://wiki.nmr-relax.com/Tutorial_for_adding_relaxation_dispersion_models_to_relax#The_relax_library.
Just in case git-svn does not preserve the file copying history, the lib/dispersion/mp05.py file was
copied from the tp02.py file.
