Add more Array methods to Actives class
Add more Array methods to Actives class

Added additional methods to the Actives class which you expect to find on
an Array-like class. These methods are: `.every()`, `.entries()`,
`.filter()`, `.findIndex()`, `.keys()`, `.lastIndexOf()`, `.pop()`,
`.shift()`, `.slice()`, `.some()` and `.values()`.

Note that now the Actives class still doesn't have all the methods you
expect on an Array-like class. This is intentional as some methods are not
desirable on this class given its intended purpose.

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