Add /occupants color command

`/occupants color on|off` to enable or disable XEP-0392 also for the
MUC occupants.

Regards
https://github.com/profanity-im/profanity/issues/1191

src/command/cmd_ac.c

@@ -708,6 +708,7 @@ cmd_ac_init(void)
     autocomplete_add(occupants_ac, "header");
     autocomplete_add(occupants_ac, "wrap");
     autocomplete_add(occupants_ac, "char");
+    autocomplete_add(occupants_ac, "color");
 
     occupants_default_ac = autocomplete_new();
     autocomplete_add(occupants_default_ac, "show");
@@ -2651,6 +2652,11 @@ _occupants_autocomplete(ProfWin *window, const char *const input, gboolean previ
         return found;
     }
 
+    found = autocomplete_param_with_func(input, "/occupants color", prefs_autocomplete_boolean_choice, previous);
+    if (found) {
+        return found;
+    }
+
     found = autocomplete_param_with_ac(input, "/occupants default hide", occupants_show_ac, TRUE, previous);
     if (found) {
         return found;

src/command/cmd_defs.c

@@ -714,6 +714,7 @@ static struct cmd_t command_defs[] =
         CMD_SYN(
             "/occupants show|hide [jid]",
             "/occupants char <char>|none",
+            "/occupants color on|off",
             "/occupants default show|hide [jid]",
             "/occupants size [<percent>]",
             "/occupants indent <indent>",
@@ -725,6 +726,8 @@ static struct cmd_t command_defs[] =
             { "show",                  "Show the occupants panel in current room." },
             { "char <char>",           "Prefix occupants with specified character." },
             { "char none",             "Remove occupants character prefix." },
+            { "color on",              "Enable generated color names (XEP-0392) for occupants" },
+            { "color off",             "Disable generated color names (XEP-0392) for occupants" },
             { "hide",                  "Hide the occupants panel in current room." },
             { "show jid",              "Show jid in the occupants panel in current room." },
             { "hide jid",              "Hide jid in the occupants panel in current room." },

src/command/cmd_funcs.c

@@ -4442,6 +4442,12 @@ cmd_occupants(ProfWin *window, const char *const command, gchar **args)
         return TRUE;
     }
 
+    if (g_strcmp0(args[0], "color") == 0) {
+        _cmd_set_boolean_preference(args[1], command, "Occupants consistent colors", PREF_OCCUPANTS_COLOR_NICK);
+        occupantswin_occupants_all();
+        return TRUE;
+    }
+
     if (g_strcmp0(args[0], "default") == 0) {
         if (g_strcmp0(args[1], "show") == 0) {
             if (g_strcmp0(args[2], "jid") == 0) {