proxy forgets packages if debuggee connects

this might fix #344

when lua-debug wait for a conencting debuggee, after the connection is accepted nothing happens.
lua-debug should send queued packages in that case, as it does in the other case where lua-debug connects to the debuggee

Author: vvvrrooomm

extension/script/common/socket.lua

@@ -85,7 +85,13 @@ return function (param)
     elseif t.mode == "listen" then
         server = assert(net.listen(t.protocol, t.address, t.port))
         function server:on_accepted(new_s)
-            return init_session(new_s)
+            local ok = init_session(new_s)
+            assert(ok)
+            if writebuf ~= '' then
+                new_s:write(writebuf)
+                writebuf = ''
+            end
+            return ok
         end
     else
         return