REORG: stconn: rename conn_stream.{c,h} to stconn.{c,h}

There's no more reason for keepin the code and definitions in conn_stream,
let's move all that to stconn. The alphabetical ordering of include files
was adjusted.
diff --git a/src/map.c b/src/map.c
index 8904c5d..76becb2 100644
--- a/src/map.c
+++ b/src/map.c
@@ -17,13 +17,13 @@
 #include <haproxy/applet.h>
 #include <haproxy/arg.h>
 #include <haproxy/cli.h>
-#include <haproxy/conn_stream.h>
 #include <haproxy/map.h>
 #include <haproxy/pattern.h>
 #include <haproxy/regex.h>
 #include <haproxy/sample.h>
 #include <haproxy/sc_strm.h>
 #include <haproxy/stats-t.h>
+#include <haproxy/stconn.h>
 #include <haproxy/tools.h>