Change the internal clipboard API to use a request based model in
order to be prepared for more advanced clipboard transfers.

We now filter incoming data, which means we can start assuming the
clipboard data is always null terminated. This allows us to clean
up a lot of the internal handling.

Use the platform independent primitives instead.

functions but non-virtual destructor". 



git-svn-id: svn://svn.code.sf.net/p/tigervnc/code/trunk@3377 3789f03b-4d11-0410-bbf8-ca57d06f2519

git-svn-id: svn://svn.code.sf.net/p/tigervnc/code/trunk@591 3789f03b-4d11-0410-bbf8-ca57d06f2519

git-svn-id: svn://svn.code.sf.net/p/tigervnc/code/branches/merge-with-vnc-4.1.1@523 3789f03b-4d11-0410-bbf8-ca57d06f2519

git-svn-id: svn://svn.code.sf.net/p/tigervnc/code/trunk@2 3789f03b-4d11-0410-bbf8-ca57d06f2519