Simple helper class to build a "sparse" array of objects based on the indexes that were added to
it. The array will be from 0 to the maximum index given. All non-set indexes will contain null
(so it's not really a sparse array, just a pseudo sparse array). The builder can also return a
CharEscaper based on the generated array.
Convert this builder into an array of chars where the maximum index is the value of the
highest character that has been seen. The array will be sparse in the sense that any unseen
index will default to null.
a "sparse" array that holds the replacement mappings.