Allow `result` to accept a `defaultValue`.
Make constants upper case and use them in place of values for easier readability.
Use `baseEach`, `baseForOwn` and `baseForIn` to reduce dependencies on `baseCreateCallback`.
Use ES6 Set to optimize `createCache`.
Cleanup `now`.
Ensure Underscore build of `result` matches Underscore.
Remove unneeded deps.
Merge `objectPool` into `sortBy`.