Add a new feature to CenH3

[molsim]

From Mailk and Henikoff, NSMB 2003, figure 4 BIoinformatic criteria for CenH3: 1) long, divergent N-term tail 2) Lack of conserved glutamine 3) longer L1 loop

[molsim]

fixed with 26020bcecf99aa71d84eb7b105e1c8a20cc7fb99