relax SVN archive

Wrote the return_gyromagnetic_ratio() for returning the desired value.

Shifted the variable docstrings to the correct position below the variable.

Converted many physical constant comments to docstrings.

Started some code to get minimise_data_setup() to return the gyromagnetic ratios.

Passed all the necessary data into minimise_data_setup().

minimise_data_setup() is now called and the data stored.

The self arg has also been added.

Shifted the grid size print out to the test_grid_size() method.

Modified generate_spin_id() to handle None and int entries in the data array.

Modified the model-free minimise() function to print out the spin_id rather than res name and num.

Updated the return_spin_from_index() function to return the spin_id string if asked.