Convergence not possible when using probability based binomial scoring

[JustinChu]

When the minimum FPR is too low for the length of a read + the false postive rate of the bf, the program aborts. Somewhat related to issue #51 .

To resolve this elegantly I could ignore read with lengths that cannot fulfil minmum FPR. However for the miBF code, some IDs for a minimum read length may be valid at a minimum FPR. To resolve these cases, I could ignore only IDs with this case. However both these cases are not likely what the user would intend.