feature: /ignore command

Like it's already implemented in irc plugin, this commit adds the /ignore command. Now you can filter messages in group chats to not be shown, based on a part of Tox ID. The ignore list of IDs is manageable in this way:
[tox]  /ignore  list
                add <ID part>
                del <ID part>

ommit messages from people with certain Tox IDs

list: show the list of ignores
add: add an ID to the list
del: delete an ID from the list

src/twc-utils.h

@@ -21,10 +21,11 @@
 #define TOX_WEECHAT_UTILS_H
 
 #include <stdlib.h>
-
 #include <tox/tox.h>
 #include <weechat/weechat-plugin.h>
 
+#include "twc-profile.h"
+
 void
 twc_hex2bin(const char *hex, size_t size, uint8_t *out);
 
@@ -73,6 +74,8 @@ twc_starts_with(struct t_weelist *list, const char *search,
 const char *
 twc_get_next_completion(struct t_weelist *completion_list,
                         const char *prev_comp);
+bool
+twc_is_id_ignored(struct t_twc_profile *profile, const char *short_id);
 
 uint32_t
 twc_uint32_reverse_bytes(uint32_t num);