Fix ref-ness of std.algorithm.map and std.container.Array

[9rnsr]

From the newsgroup:
http://forum.dlang.org/thread/ceftaiklanejfhodbpix@forum.dlang.org#post-uwnpibltiobnsjtcygwo:40forum.dlang.org

[DmitryOlshansky]

About Array - I don't think so. It was meant to never leak an address of element.
It was called sealed container.

[alexrp]

Can't take the address of an element? That's quite the useless array...

[DmitryOlshansky]

You don't get it - it was supposed that e.g.
ar[x] = bleh;
would call opIndexAssign
then arr[].front = x;
should also do the correct forwarding thing. Apparently it didn't.

[9rnsr]

From digitalmars.D newsgroup, @andralex says:

Hmm, that has a couple of issues.

First, map that modifies things in place is a bug more often than a feature given that the caller of map may use front() an arbitrary number of times. So I see little intentional and legitimate use for things like map!"a += 2"(range).

Second, the return by value from Array is intentional and has to do with sealing. Array is intended to never escape the addresses of its elements. That way, the collection is "sealed" in the sense there can never be uncontrolled pointers to its elements. This allows using efficient allocation strategies for the array without compromising its safety.

I can agree with his argument, so I close this pull request.