[boost] boost::optional -- updates for C++11 move semantics

Subject: [boost] boost::optional -- updates for C++11 move semantics
From: Diggory Hardy (lists_at_[hidden])
Date: 2013-02-05 09:26:32

Dear list,

I wanted something like boost::optional, but with support for move-
construction/assignment, so I went ahead and had a go at patching it.

Attached is based on boost 1.49 (Ubuntu package). Could someone please review? 
I've not contributed to boost before. The changes at least aren't too 
complicated, but:
1) I'm not entirely sure if the move constructor (line 636) and swap function 
(line 1046) are implemented in the best way (also see line 279),
2) and I have no idea how is_[not_]reference_tag (line 486) works.
3) There should maybe also be a unit test.

Of course, I am happy for my contributions to be published under the boost 
licence.

Regards,
Diggory