base: split out the VncServer into a VncInput and Server classes

This patch adds a VncInput base class which VncServer inherits from.
Another class can implement the same interface and be used instead
of the VncServer, for example a class that replays Vnc traffic.

--HG--
rename : src/base/vnc/VncServer.py => src/base/vnc/Vnc.py
rename : src/base/vnc/vncserver.cc => src/base/vnc/vncinput.cc
rename : src/base/vnc/vncserver.hh => src/base/vnc/vncinput.hh

src/base/vnc/SConscript

@@ -41,6 +41,7 @@ Import('*')
 
 Source('convert.cc')
 
-SimObject('VncServer.py')
+SimObject('Vnc.py')
+Source('vncinput.cc')
 Source('vncserver.cc')
 DebugFlag('VNC')