The new viewer stores the framebuffer in a native format, instead of

The new viewer stores the framebuffer in a native format, instead of
converting it on each render like the old one. That means we have to change
how we deal with colour maps and make sure it is updated before any changes
to the framebuffer.

git-svn-id: svn://svn.code.sf.net/p/tigervnc/code/trunk@4589 3789f03b-4d11-0410-bbf8-ca57d06f2519