Equations added

This partially addresses issue #321 by adding these equations: ace, enspie, heip_e, fisher_alpha, kempton_taylor_q, mcintosh_e, menhinick, shannon, simpson, and strong. In addition, variable definitions were added to berger_parker_d and to brillouin_d. 
I think we should actually provide the S = alpha * log (1 + N/alpha) equation as in: https://www.dropbox.com/s/sz1g8s9cmq2oyax/Screenshot%202014-08-07%2017.15.25.png