patch 8.2.0516: client-server code is spread out

Problem:    Client-server code is spread out.
Solution:   Move client-server code to a new file. (Yegappan Lakshmanan,
            closes #5885)
diff --git a/Filelist b/Filelist
index 25bfb4c..422a0d0 100644
--- a/Filelist
+++ b/Filelist
@@ -30,6 +30,7 @@
 		src/channel.c \
 		src/charset.c \
 		src/cindent.c \
+		src/clientserver.c \
 		src/clipboard.c \
 		src/cmdexpand.c \
 		src/cmdhist.c \
@@ -203,6 +204,7 @@
 		src/proto/channel.pro \
 		src/proto/charset.pro \
 		src/proto/cindent.pro \
+		src/proto/clientserver.pro \
 		src/proto/clipboard.pro \
 		src/proto/cmdexpand.pro \
 		src/proto/cmdhist.pro \