rename underscore methods after the native [] method names, aliases for ruby versions

Even though the native methods have worse names (forEach, every, some),
since this library is trying to smooth over the native language it makes
more sense to use the native names, and provide aliases for more sensible
names from other languages, not the other way around.

Note this doesn't change any external usage, it just makes more sense.

This should also be useful for abstraction purposes for building underscore
functions, something like:

  addFn('some', {has_native: true, our_version: function () {...}})

this way we could feature detect on load for native versions and build a
function, and also have the option to turn off native versions for testing
our implementation.

I Also standardized the comments to look like:
  Delegates to JavaScript 1.x's native y if available.
(cherry picked from commit 7ec8d12d6c4644dcdade95c06125aca26f3e748f)