solrium: General Purpose R Interface to 'Solr'

#' @param name Name of a collection or core. Or leave as \code{NULL} if not needed.
#' @param callopts Call options passed on to [crul::HttpClient]
#' @param raw (logical) If TRUE, returns raw data in format specified by wt param
#' @param parsetype (character) One of 'list' or 'df'
#' @param concat (character) Character to concatenate elements of longer than length 1.
#' Note that this only works reliably when data format is json (wt='json'). The parsing
#' is more complicated in XML format, but you can do that on your own.
#' @param progress a function with logic for printing a progress
#' bar for an HTTP request, ultimately passed down to \pkg{curl}. only supports 
#' \code{httr::progress} for now. See the README for an example.
#' @param ... Further args to be combined into query
#'
#' @section More like this parameters:
#' \itemize{
#'  \item q Query terms, defaults to '*:*', or everything.
#'  \item fq Filter query, this does not affect the search, only what gets returned
#'  \item mlt.count The number of similar documents to return for each result. Default is 5.
#'  \item mlt.fl The fields to use for similarity. NOTE: if possible these should have a stored
#' TermVector DEFAULT_FIELD_NAMES = new String[] {"contents"}
#'  \item mlt.mintf Minimum Term Frequency - the frequency below which terms will be ignored in
#' the source doc. DEFAULT_MIN_TERM_FREQ = 2
#'  \item mlt.mindf Minimum Document Frequency - the frequency at which words will be ignored which
#' do not occur in at least this many docs. DEFAULT_MIN_DOC_FREQ = 5
#'  \item mlt.minwl minimum word length below which words will be ignored.
#' DEFAULT_MIN_WORD_LENGTH = 0
#'  \item mlt.maxwl maximum word length above which words will be ignored.
#' DEFAULT_MAX_WORD_LENGTH = 0
#'  \item mlt.maxqt maximum number of query terms that will be included in any generated query.
#' DEFAULT_MAX_QUERY_TERMS = 25
#'  \item mlt.maxntp maximum number of tokens to parse in each example doc field that is not stored
#' with TermVector support. DEFAULT_MAX_NUM_TOKENS_PARSED = 5000
#'  \item mlt.boost (true/false) set if the query will be boosted by the interesting term relevance.
#' DEFAULT_BOOST = false
#'  \item mlt.qf Query fields and their boosts using the same format as that used in
#' DisMaxQParserPlugin. These fields must also be specified in mlt.fl.
#'  \item fl Fields to return. We force 'id' to be returned so that there is a unique identifier
#' with each record.
#'  \item wt (character) Data type returned, defaults to 'json'. One of json or xml. If json,
#' uses \code{\link[jsonlite]{fromJSON}} to parse. If xml, uses \code{\link[XML]{xmlParse}} to
#' parse. csv is only supported in \code{\link{solr_search}} and \code{\link{solr_all}}.
#'  \item start Record to start at, default to beginning.
#'  \item rows Number of records to return. Defaults to 10.
#'  \item key API key, if needed.
#' }