Add `drop`, `dropRight`, `dropRightWhile`, `dropWhile`, `take`, `takeRight`, `takeRightWhile`, `takeWhile`, `negate`, `baseValues`, `valuesIn`, `baseFor`, `baseForRight`, `keysIn`, `kebabCase`, `pad`, `padLeft`, `padRight`, `repeat`, `snakeCase`, `startsWith`, `escapeRegExp`, `createCompounder`, `createPad`, `deburrLetter`, and `truncate`.
Remove `createIterator` and `iteratorTemplate`.
Tweak doc notes and rename `callback` vars to `predicate` where appropriate.
Add new methods to categories and make categories modules follow ES6 module spec.
Make use of new methods.