Rename Quant to Twig

As I wrote in the README, Merriam-Webster has the following definition
for twig:

  twig (transitive verb)
  1 : notice, observe
  2 : to understand the meaning of : comprehend

Change-Id: I66e879cddd8fa3b1c1460947f6b39cae410c0a2e
Reviewed-on: https://gerrit.causes.com/22014
Reviewed-by: Jimmy Kittiyachavalit <jimmy@causes.com>
Tested-by: Jimmy Kittiyachavalit <jimmy@causes.com>