new error-handling routines in FDRreg functions seem to be catching the previous bugs.  Things to be aware of:
1) a non-convergent fit inside the iterative FDR regression piece
2) an estimate of m_1(z), the marginal density under the alternative hypothesis, not being strictly zero across the entire domain.  Right now this is handled via thresholding m_1(z) below at the .Machine$double.eps, which is probably not the best approach
added small ridge term to Bayesian FDR reg; finished sim study