* Don't add duplicate assembly references
* Create a HintPath for assembly references that exist in a project reference directory (fixes an xbuild issue)
* Add a VS2010 target
git-svn-id: http://libopenmetaverse.googlecode.com/svn/libopenmetaverse/trunk@3075 52acb1d6-8a22-11de-b505-999d5b087335