Rename ConnParams to ClientParams

Now that we've split out server state to ServerParams, ConnParams
only contains state for a client. Rename the class and variables
to reflect this.
diff --git a/common/rfb/RREEncoder.cxx b/common/rfb/RREEncoder.cxx
index 7287e7e..8358549 100644
--- a/common/rfb/RREEncoder.cxx
+++ b/common/rfb/RREEncoder.cxx
@@ -47,7 +47,7 @@
 
 bool RREEncoder::isSupported()
 {
-  return conn->cp.supportsEncoding(encodingRRE);
+  return conn->client.supportsEncoding(encodingRRE);
 }
 
 void RREEncoder::writeRect(const PixelBuffer* pb, const Palette& palette)