allow groupchat sidebar to scroll

src/groupchat.h

@@ -3,11 +3,13 @@
  */
 
 #define SIDEBAR_WIDTH 16
+#define SDBAR_OFST 2    /* Offset for the peer number box at the top of the statusbar */
 
 typedef struct {
     int chatwin;
     bool active;
     int num_peers;
+    int side_pos;    /* current position of the sidebar - used for scrolling up and down */
     uint8_t *peer_names;
     uint8_t *oldpeer_names;
 } GroupChat;