Add initial support for XEP-0392

The last 3 commits added basic support.
Thanks @aaptel!

This commit adds basic settings interface to use it.
See `/color on|off`.

We still have to enable settings for color blindness.
And maybe another setting to decide whether to color the
occupantslist/roster with the same algo.

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

src/command/cmd_ac.c

@@ -1479,7 +1479,7 @@ _cmd_ac_complete_params(ProfWin *window, const char *const input, gboolean previ
 
     // autocomplete boolean settings
     gchar *boolean_choices[] = { "/beep", "/intype", "/states", "/outtype", "/flash", "/splash",
-        "/history", "/vercheck", "/privileges", "/wrap", "/carbons", "/lastactivity" };
+        "/history", "/vercheck", "/privileges", "/wrap", "/carbons", "/lastactivity", "/color" };
 
     for (i = 0; i < ARRAY_SIZE(boolean_choices); i++) {
         result = autocomplete_param_with_func(input, boolean_choices[i], prefs_autocomplete_boolean_choice, previous);

src/command/cmd_defs.c

@@ -2294,6 +2294,21 @@ static struct cmd_t command_defs[] =
         CMD_NOARGS
         CMD_NOEXAMPLES
     },
+
+    { "/color",
+        parse_args, 1, 1, &cons_color_setting,
+        CMD_NOSUBFUNCS
+        CMD_MAINFUNC(cmd_color)
+        CMD_TAGS(
+            CMD_TAG_UI)
+        CMD_SYN(
+            "/color on|off")
+        CMD_DESC(
+            "Settings for consistent color generation for nicks (XEP-0392).")
+        CMD_ARGS(
+            { "on|off", "Enable or disable nick colorization for MUC nicks." })
+        CMD_NOEXAMPLES
+    },
 };
 
 static GHashTable *search_index;

src/command/cmd_funcs.c

@@ -8626,3 +8626,10 @@ cmd_paste(ProfWin *window, const char *const command, gchar **args)
 
     return TRUE;
 }
+
+gboolean
+cmd_color(ProfWin *window, const char *const command, gchar **args)
+{
+    _cmd_set_boolean_preference(args[0], command, "Consistent color generation for nicks", PREF_COLOR_NICK);
+    return TRUE;
+}

src/command/cmd_funcs.h

@@ -223,4 +223,6 @@ gboolean cmd_save(ProfWin *window, const char *const command, gchar **args);
 gboolean cmd_reload(ProfWin *window, const char *const command, gchar **args);
 
 gboolean cmd_paste(ProfWin *window, const char *const command, gchar **args);
+
+gboolean cmd_color(ProfWin *window, const char *const command, gchar **args);
 #endif