Creates a string with the information for a single SNP. The information is coded as A-count:T-count:C-count:G-count:N-count:deletion-count. Note that we assume that the reference allele is always A and the alternative is always T.
strg2sync(reference, alternative)
a character string coded as A-count:T-count:C-count:G-count:N-count:deletion-count.
an integer representing the number of reads with the reference allele.
an integer representing the number of reads with the alternative allele.