get_quad_count: Get the count of events based on Quad category
In LaDilettante/icewsr: Various utility functions to work with ICEWS database

get_quad_count takes a vector of quad categories (including verbal/material cooperation/conflict), determines the corresponding CAMEO codes, then get the counts for the specified source/target countries and date by calling get_CAMEO_count

1 2	get_quad_count(conn, quad, date = NULL, source.country = NULL, target.country = NULL)

`conn`	A MySQL connection to the ICEWS database. Supply your credentials to `conn <- dbConnect(MySQL(), user="username", password="password", dbname="event_data", host="our.host.ip")`
`quad`	A string indicates a quad category, i.e. one of `verb.coop, verb.conf, matl.coop, matl.confl)`
`date`	A string in the YYYYMMDD format. If `NULL`, will count events on any date
`source.country`	A string specifying the ISOA3Code of the source country. If `NULL`, will count events from all countries
`target.country`	A string specifying the ISOA3Code of the target country. If `NULL`, will count events targeted at all countries

## Not run: 
quads <- c("verb.coop", "verb.conf", "matl.coop", "matl.conf")
# Get quad counts between all country-dyads in a given date
result1 <- ldply(quads, .fun=getIcewsQuad, date="20021025")
# Get quad counts between one dyad for all dates
result2 <- ldply(quads, .fun=getIcewsQuad,
                source.country="AFG", target.country="ALB")
# Get quad counts for one dyad in one date
result3 <- ldply(quads, .fun=getIcewsQuad, date="20021025", source.country="AFG", target.country="ALB")

## End(Not run)