Add groupchat side panel & add new callback

src/groupchat.h

@@ -2,4 +2,18 @@
  * Toxic -- Tox Curses Client
  */
 
+/* The sidebar will take up y/n of the window width where x is the full width of the window */
+#define SIDEBAR_WIDTH 16
+#define CHATBOX_HEIGHT 4
+
+/* Limits # of peers in sidepanel (make this go away) */
+#define MAX_GROUP_PEERS 100    
+
+typedef struct {
+    int chatwin;
+    bool active;
+    int num_peers;
+    uint8_t peer_names[MAX_GROUP_PEERS][TOX_MAX_NAME_LENGTH];
+} GroupChat;
+
 int init_groupchat_win(ToxWindow *prompt, Tox *m, int groupnum);