Improve inflation adjustment function about grattan HOT 1 CLOSED

The general inflator now works great. Thanks Hugh.

Here's a demonstration that it's working:

construction_indices <-
read_excel("./data-raw/Construction-price-index.xlsx", sheet = "Data") %>%
mutate(Time = as.yearqtr(Time)) %>%
as.data.table

y<- c(1, 2, 3, 4, 5)
output <- general_inflator(x = y, from = as.yearqtr("2014 Q1"), to = as.yearqtr("2015 Q1"), inflator_table = construction_indices )

Where: "./data-raw/Construction-price-index.xlsx" is the ABS construction price index series.

from grattan.