calculateLWDCountMetrics: Calculate LWD metrics
In jasonelaw/nrsa: Calculate metrics for NRSA protocol data.

This function calculates LWD counts within each site, size class, and whether it is within the bankfull area

1	calculateLWDCountMetrics(uid, size.class, count, is.wadeable, epa.names = T)

`uid`	vector of site-visit indicators
`size.class`	A vector of size class codes (e.g., WSDSL, DXDLL, ...)
`count`	vector of counts of LWD pieces
`is.wadeable`	logical describing whether the site is wadeable or not
`epa.names`	should the metrics be in data.frame format with EPA's names or in contingency table style. Defaults to EPA style.