Linear spatial interpolation

  This module spatially interpolates the input traces into the output space by a bilinear interpolator in the midpoint space and a nearest-neighborhood interpolator along the offset and azimuth axes.

• spat_interp_real =  spat_interp_lin_near_real
• spat_interp_complex =  spat_interp_lin_near_complex

The interface of spat_interp_lin_near_real_init and spat_interp_lin_near_complex_init are the same. For example the interface of spat_interp_lin_near_real_init is

function spat_interp_near_near_real_init (out_sailing_lines) result (stat)
integer                 :: stat
logical, optional       :: out_sailing_lines

The parameter out_sailing_lines is defaulted to .false. when is not present, or the initialization function is not called.