document result of applying _.min or _.max to an empty list
Merge pull request #1619 from davidchambers/infinity

document result of applying _.min or _.max to an empty list
update _.has to return false for null/undefined

The current behaviour (throwing a TypeError) is not helpful, and likely
not deliberate.
Merge pull request #1624 from davidchambers/has

update _.has to return false for null/undefined
Expose the memoize cache.
Merge pull request #1627 from braddunbar/memoize-cache

Expose the memoize cache.
Tweak memoize cache.
fix throttle and debounce to be re-entrant
remove context and arg variables
make sequence of calls clear for re-entrant tests
Merge pull request #1629 from dontfidget/re-entrant

fix throttle and debounce to be re-entrant
one-liner short if statements