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/CConn.cxx b/vncviewer/CConn.cxx
index 789cf09..d7f57b5 100644
--- a/vncviewer/CConn.cxx
+++ b/vncviewer/CConn.cxx
@@ -65,8 +65,9 @@
 // 64 colours (2 bits per component)
 static const PixelFormat lowColourPF(8, 6, false, true,
                                      3, 3, 3, 4, 2, 0);
-// 256 colours (palette)
-static const PixelFormat mediumColourPF(8, 8, false, false);
+// 256 colours (2-3 bits per component)
+static const PixelFormat mediumColourPF(8, 8, false, true,
+                                        7, 7, 3, 5, 2, 0);
 
 CConn::CConn(const char* vncServerName, network::Socket* socket=NULL)
   : serverHost(0), serverPort(0), desktop(NULL),
@@ -342,7 +343,7 @@
 
 void CConn::setColourMapEntries(int firstColour, int nColours, rdr::U16* rgbs)
 {
-  desktop->setColourMapEntries(firstColour, nColours, rgbs);
+  vlog.error("Invalid SetColourMapEntries from server!");
 }
 
 void CConn::bell()