Implemented BigString, which automatically turns off the summary flag
when saving.

Overloaded .replaceItemValue with an additional boolean to force summary
flag.

Performance improvements on DocumentScanner with pre-compiled regex
pattern.

Improved DocumentComparator to use Document.get(Object) so that it can
support both field names and @formula keys. Also made the Comparator
list-aware, so multi-value results are accepted for comparisons.

Signed-off-by: Nathan T Freeman <nathan.freeman@redpilldevelopment.com>