GMPR: Computes the GMPR size factor
In chloelulu/ZicoSeq: Has not been decided

Computes the GMPR size factor

1	GMPR(comm, intersect.no = 4, ct.min = 2, verbose = FALSE)

`comm`	a matrix of counts, row - features (OTUs, genes, etc) , column - sample
`intersect.no`	the minimum number of shared features between sample pair, where the ratio is calculated
`ct.min`	the minimum number of counts required to calculate ratios ct.min = 5 has better results
`verbose`	suppress output

A list that contains:

`gmpr`	the GMPR size factors for all samples; Samples with distinct sets of features will be output as NA.
`nss`	number of samples with significant sharing (> intersect.no) including itself