script: expose theme_register to python, perl, ruby, lua, tcl, javascript, php, guile

Add weechat.theme_register (name, overrides) to all eight script
languages. Each binding is a mechanical translation of the same
signature:

  - name:      string
  - overrides: language-native dict / hash / associative array of
               full_option_name -> value strings
  - returns:   pointer-as-string of the registered t_theme (empty
               string on failure)

Each binding converts the dict to a struct t_hashtable using the
existing per-language helper (weechat_python_dict_to_hashtable,
weechat_perl_hash_to_hashtable, weechat_ruby_hash_to_hashtable,
weechat_lua_tohashtable, weechat_tcl_dict_to_hashtable,
weechat_js_object_to_hashtable, weechat_php_array_to_hashtable,
weechat_guile_alist_to_hashtable), calls weechat_theme_register,
frees the temporary hashtable, and returns the result. The new
function is registered right after the config_* functions so the API
listing stays grouped by topic.

PHP also receives a new arginfo entry (string, array -> string) in
both weechat-php_arginfo.h and weechat-php_legacy_arginfo.h.

This is plumbing only - the underlying theme_register function is
already covered by tests/unit/core/test-core-theme.cpp
(TEST(CoreTheme, Register)). No script-side tests are added here.

src/plugins/php/weechat-php-api.c

@@ -2175,6 +2175,33 @@ API_FUNC(config_unset_plugin)
     API_RETURN_INT(result);
 }
 
+API_FUNC(theme_register)
+{
+    zend_string *z_name;
+    zval *z_overrides;
+    char *name;
+    struct t_hashtable *overrides;
+    const char *result;
+
+    API_INIT_FUNC(1, "theme_register", API_RETURN_EMPTY);
+    if (zend_parse_parameters (ZEND_NUM_ARGS(), "Sa", &z_name,
+                               &z_overrides) == FAILURE)
+        API_WRONG_ARGS(API_RETURN_EMPTY);
+
+    name = ZSTR_VAL(z_name);
+    overrides = weechat_php_array_to_hashtable (z_overrides,
+                                                WEECHAT_SCRIPT_HASHTABLE_DEFAULT_SIZE,
+                                                WEECHAT_HASHTABLE_STRING,
+                                                WEECHAT_HASHTABLE_STRING);
+
+    result = API_PTR2STR(weechat_theme_register ((const char *)name,
+                                                 overrides));
+
+    weechat_hashtable_free (overrides);
+
+    API_RETURN_STRING(result);
+}
+
 API_FUNC(key_bind)
 {
     zend_string *z_context;