Added the multi-quantum CPMG and R1rho experiment types to the dispersion variables.

This is needed for the 'MQ NS CPMG 2-site' model.

This follows the tutorial for adding relaxation dispersion models at:
http://wiki.nmr-relax.com/Tutorial_for_adding_relaxation_dispersion_models_to_relax#Creating_a_new_experiment_type.
Added relaxation dispersion model lists for the MQ R1rho models.

These are stubs as no MQ R1rho models are yet supported by relax.
Added support for the MQ dispersion data type to the specific_analyses.relax_disp.disp_data module.

This is needed for the 'MQ NS CPMG 2-site' model.

This follows the tutorial for adding relaxation dispersion models at:
http://wiki.nmr-relax.com/Tutorial_for_adding_relaxation_dispersion_models_to_relax#Creating_a_new_experiment_type.
Added support for the MQ dispersion data types to the rest of relax.

This is needed for the 'MQ NS CPMG 2-site' model, and the changes affect the dispersion data checks
and the dispersion target functions.

This follows the tutorial for adding relaxation dispersion models at:
http://wiki.nmr-relax.com/Tutorial_for_adding_relaxation_dispersion_models_to_relax#Creating_a_new_experiment_type.
Updated the Relax_disp.test_sprangers_cpmg_data_auto_analysis system test for 'MQ CPMG' data.

This also affects the script in the shared_data test suite directory.  The relax_disp.exp_type user
function exp_type argument has been changed from 'CPMG' to 'MQ CPMG'.