Add additional physics methods for MAST

[samueljackson92]

A first pass at adding MAST data was added in #488. However it would be good to add some additional physics methods that are currently missing for consistency:

• z_cur - estimated vertical position of the centroid
• z_prog - programmed vertical position of the centroid
• z_error - error between actual and programmed
• p_oh - ohmic power
• n_equal_1_mode - RMS amplitude of n=1 mode
• ne_peaking - Thomson density peaking factor
• te_peaking - Thomson temperature peaking factor
• pressure_peaking - Thomson pressure peaking factor
• te_width - Thomson width from Gaussian fit
• p_rad_peaking - radiated power peaking factor