supporting X, B and Z in predict hyp input

[missuse]

predict_hyp could support unknown amino acids symbols X (any), B (D or N) and Z (E or Q) if they occur up to once or even twice in subsequence.

This could proceed by generating all possible subsequences (this is why a limit of X is needed 20 * 20 is manageable but 20 * 20 * 20 is too much per subsequence), predicting Hyp probability in them and retuning the probability that is the min, max or floor(median) of predictions based on an additional argument in the function.