Minor fixes

- [#3225](https://svn.boost.org/trac/boost/ticket/3225) already can be closed, however there are no tests about that.
  - 95d2a11 Add tests for [#3225](https://svn.boost.org/trac/boost/ticket/3225)
- Metafuncsions and documents: `copy` / `move`
  - 916df63 Add result_of::{copy,move}, close [#5886](https://svn.boost.org/trac/boost/ticket/5886)
- SFINAE-friendly result_of
  - 465c3f2 result_of::{copy,move,swap} are now SFINAE-friendly

Tested under x86_64-linux-gnu with GCC 4.8.3/Clang 3.4 (both of C++98 / C++11 mode).