Optional: fix some unused parameter warnings

svn path=/trunk/boost/optional/; revision=81031
Remove extra :'s.  Fixes #7973.

svn path=/trunk/libs/optional/; revision=82909
Some doc typos.  Fixes #7602.

svn path=/trunk/libs/optional/; revision=82910
Correct definition of operator unspecified-bool-type.  Make reference for is_initialized point to this operator.  Fixes #6364.

svn path=/trunk/libs/optional/; revision=82911
Replace deprecated function reset in examples.  Fixes #765.

svn path=/trunk/libs/optional/; revision=82912
Work around msvc bug when explicitly destroying a class with a virtual base.  Fixes #5940.

svn path=/trunk/libs/optional/; revision=82915
Use __may_alias__ instead of may_alias.  Fixes #6410.

svn path=/trunk/boost/optional/; revision=82919
Add a forward declaration of the ostream operator for optional.  Fixes #2103.

svn path=/trunk/boost/optional/; revision=82930
Update optional documentation.

svn path=/trunk/libs/optional/; revision=82931
Try to fix VC8.

svn path=/trunk/libs/optional/; revision=83445