Remove full support for colour maps

Gets rid of a loooot of code and complexity.

Colour map clients are still supported through an
automatically generated map, but we lose the ability to
develop a client or server that uses colour maps
internally.
diff --git a/vncviewer/Win32PixelBuffer.cxx b/vncviewer/Win32PixelBuffer.cxx
index 626bb96..4ee15ce 100644
--- a/vncviewer/Win32PixelBuffer.cxx
+++ b/vncviewer/Win32PixelBuffer.cxx
@@ -40,7 +40,7 @@
 PlatformPixelBuffer::PlatformPixelBuffer(int width, int height) :
   FullFramePixelBuffer(rfb::PixelFormat(32, 24, false, true,
                                         255, 255, 255, 16, 8, 0),
-                       width, height, NULL, NULL),
+                       width, height, NULL),
   bitmap(NULL)
 {
   BITMAPINFOHEADER bih;