Added routine to compute omega values and test them.

compute_omega is basically a stripped-down copy of compute_omega_prime.
Added routine to calculate values for Figure 2 and PI constant

Added Figure 2 code to main b/c it isn't really part of the operator code
and the omega values are only used here.
Coded and lightly tested routine to create Figure 2.

Figure 2 is the sinc function with fundamental spline approximations.