relax SVN archive

Completed the gyromagnetic ratio part of the model-free minimise_data_setup() method.

Modified generic_fns.align_tensor.kappa() to use the new return_gyromagnetic_ratio() function.

Wrote the return_atomic_mass() function for returning the desired atomic mass.

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.