In-place array functions

[jariji]

In-place operations are useful for performance and mutating stateful objects so it could be helpful to have in-place versions of common array functions.

There are various array functions like map! that take dest, src arguments but the docstring warns against overlapping arguments, so there isn't a recommended way to do in-place mutation.

• map!(f, xs)
• filter!(f, xs)
• accumulate!(op, xs)
• circshift!(xs, n)
• cumsum!(xs)
• cumprod!(xs)

We already have in-place reverse!, invpermute!, permute!.