Maybe move to R6 setup

[sckott]

if staring using R6 package, could then have separate objects for different connections, so easier to do > 1 connections per R session - not sure of best way to use these connections though - either pass in as a parameter to methods like

con <- solr_connect()
solr_search(con, q = "*:*")

or if we modify include methods in the connection object, then e.g,

con <- solr_connect()
con$solr_search(q = "*:*")

no longer need to pass in connection object as a parameter, but breaks code in diff. way in that you have to call methods on a R6 class

would help #99 by we could make explicit methods for params vs. data, which then go into query params and body, respectively

[sckott]

if this is done, may need to roll a diff. pkg as solrium2