Rename `pk.calc.auciv()` to `pk.calc.auxciv()` and generalize its use

[billdenney]

Please do the same operations as suggested in #494, but for the pk.calc.auciv() and pk.calc.aumciv() functions.

pknca/R/auciv.R

Lines 203 to 245 in aac6a30

	#' Calculate AUMC for intravenous dosing with C0 back-extrapolation
	#'
	#' @details Analogous to pk.calc.auciv but for AUMC.
	#' Replaces the first AUMC interval (from measured C0) with one using extrapolated c0.
	#'
	#' @inheritParams pk.calc.auxc
	#' @param c0 The concentration at time 0 (extrapolated)
	#' @param aumc The AUMC calculated without c0 adjustment (e.g., aumcall, aumclast)
	#' @return The AUMC with IV back-extrapolation applied
	#' @export
	pk.calc.aumciv <- function(conc, time, c0, aumc, ..., options = list(), check = TRUE) {
	if (check) {
	assert_conc_time(conc = conc, time = time)
	data <- clean.conc.blq(conc, time, options = options, check = FALSE)
	} else {
	data <- data.frame(conc = conc, time = time)
	}
	if (!(0 %in% time)) {
	return(structure(NA_real_, exclude = "No time 0 in data"))
	} else if (is.na(c0)) {
	return(structure(NA_real_, exclude = "c0 is not calculated"))
	}
	# AUMC for first interval using measured concentrations
	aumc_first <- pk.calc.aumc.last(
	conc = data$conc[1:2],
	time = data$time[1:2],
	...,
	check = FALSE
	)
	# AUMC for first interval using extrapolated c0
	aumc_second <- pk.calc.aumc.last(
	conc = c(c0, data$conc[2]),
	time = data$time[1:2],
	...,
	check = FALSE
	)
	aumc_final <- aumc + aumc_second - aumc_first
	aumc_final
	}