Fix group ignore functionality

Ignoring a peer now persists if they leave/disconnect and rejoin the group.
In addition, ignore status is now displayed in the peer list sidebar
as a red # symbol.

src/groupchats.h

@@ -47,6 +47,7 @@ typedef struct GroupPeer {
     uint8_t          public_key[TOX_GROUP_PEER_PUBLIC_KEY_SIZE];
     TOX_USER_STATUS  status;
     Tox_Group_Role   role;
+    bool             is_ignored;
     uint64_t         last_active;
 } GroupPeer;
 
@@ -56,6 +57,9 @@ typedef struct {
     uint32_t   num_peers;     /* Number of peers in the chat/name_list array */
     uint32_t   max_idx;       /* Maximum peer list index - 1 */
 
+    uint8_t    **ignored_list; /* List of keys of peers that we're ignoring */
+    uint16_t   num_ignored;
+
     char       group_name[TOX_GROUP_MAX_GROUP_NAME_LENGTH + 1];
     size_t     group_name_length;
     uint32_t   groupnumber;
@@ -108,4 +112,9 @@ void redraw_groupchat_win(ToxWindow *self);
  */
 GroupChat *get_groupchat(uint32_t groupnumber);
 
+/**
+ * Toggles the ignore status of the peer associated with `peer_id`.
+ */
+void group_toggle_peer_ignore(uint32_t groupnumber, int peer_id, bool ignore);
+
 #endif /* #define GROUPCHATS_H */