Integer overflow

[FelixErnst]

Hi,

Similiar to #432 I get a warning on an integer overflow when running dada

dadaForward <- dada(filesForwardFiltered, err = errForward,
                                      multithread = TRUE)
...
## Warning in rval[, 1:ncol(tt)] + tt: NAs produced by integer overflow

The datasets constists of ~2300 samples and it occurs 4 times for the forward reads and three times for the reverse reads. The location is quite easy to pin point: accumulateTrans

https://github.com/benjjneb/dada2/blob/82f4660b450038413e169a5a8e6a8b103fa0e067/R/errorModels.R#L379

I guess a switch to a double matrix might solve the issue here as well.

Please let me know, what you think and wether this a problem for the analysis. Thanks!

Felix