Adding boost::is_complex to type_traits.hpp

[ejgrace]

Following a discussion on boost-users I am adding this
to the bug system so it doesn't get lost.  

Can someone add a boost::is_complex<T> trait so that
checks for complex numbers can be made.  This is a
common requirement in templated scientific code as
complex numbers sometimes need to be treated differently.

Attached is my implementation, please feel free to
incorperate it.

[ejgrace]

Logged In: YES 
user_id=988665

I was writing some new code and wondered what ever happened
to boost::is_complex,

http://article.gmane.org/gmane.comp.lib.boost.user/13692

stumbling across a few posts and my original bug report it
appears that I did not actually upload my implementation! 
Sorry I have now attached it.

[John Maddock]

This has now (finally!) been added to SVN trunk.