Falwa

Added two new functions that allows computation of LWA based on *prescribed* equivalent-latitudes:
- barotropic_input_Qref_to_compute_LWA
- qgpv_input_Qref_to_compute_LWA

- Included a function 'static_stability' to compute static stability from potential temperature field.
- Fixed a bug in outputing equivalent latitude in the function 'qgpv_Eqlat_LWA'. Other related subroutines are not affected.
- A beta version of function 'Solve_URef_noslip_hemisphere' is updated. It can only be used to compute eddy-free reference state in no-slip boundary conditions.