Due to performance reasons (parsing time), Lodash is no longer included as a part of every patch.
All of the non-standard methods like RemoveWhere, Map (full list available here) were also removed due to additional parsing time needed to perform JS operations. Most of them can be easily substituted with ECMAScript 5.1 or 6 capabilities built-in in the Jint engine (check examples).
The ability to write your own custom functions and share them between patches has been dropped. Functions can be inlined inside a patching script and will work.