filesystem::path as a template

[streetraider]

I suggest boost::filesystem::path to be a template:

template <typename CharType = char>
class path;

Current path will be used as path<char>.

Of course it's unable to use path<wchar_t> for file
operations like open(), rename() and so on with current
C++ library. These function may take path<char> as
parameters.

But it's very useful to have path<wchar_t> dealing with
filenames! Any will be able to use it and pass them for
WinAPI functions by example, or use in any database
that support wide chars.

At second, I think path::extention() member function
will be useful to exctact extention of the file, such
as ".html" (or just "html") for "foo/bar.html".