All imported JMP question must be marked as concerning population

Computation was broken because absolute value was not computed
during import.
Increase percentage precision to match JMP computing results

Because Excel files sometime use simple formula for manually entered
values. So the value is actually a float with several decimals that
we need to import as such in order to get correct final results.
Remove obsolete .gitignore
Refactor Hydrator for speed improvements

It is now back to its original concept of extracting only fields
asked on an object basis and not on a type basis. This allow us to
have different fields for a Filter and its originalFilter. In most
cases it will return less fields than before.