Added warning to symbolic equilibria function if <2^N equilibria found

Solve does not find equilibria located at +/- Inf. Thus at singularities, less than 2^N equilibria will be found by shc_lv_symequilibria(), e.g., alp=1, bet=1, nu=2. The important equilibria in the non-negative orthant are always found, however.

Signed-off-by: Andrew D. Horchler <adh9@case.edu>