i18n: Add support for translating the class reference

- Parse `.po` files from `doc/translations/*.po` like already done
  with `editor/translations/*.po`.
- Add logic to register a doc translation mapping in `TranslationServer`
  and `EditorSettings`.
- Add `DTR()` to lookup the doc translation mapping (similar to `TTR()`).
  Strings are automatically dedented and stripped of whitespace to ensure
  that they would match the translation catalog.
- Use `DTR()` to translate relevant strings in `EditorHelp`,
  `EditorInspector`, `CreateDialog`, `ConnectionsDialog`.
- Small simplification to `TranslationLoaderPO`, the path argument was
  not really meaningful.

1 files changed, 13 insertions, 4 deletions

diff --git a/core/translation.cpp b/core/translation.cpp
index 7399fa5619..df3661e5d0 100644
--- a/core/translation.cpp
+++ b/core/translation.cpp
@@ -1176,7 +1176,6 @@ void TranslationServer::setup() {
 		set_locale(OS::get_singleton()->get_locale());
 	fallback = GLOBAL_DEF("locale/fallback", "en");
 #ifdef TOOLS_ENABLED
-
 	{
 		String options = "";
 		int idx = 0;
@@ -1189,7 +1188,6 @@ void TranslationServer::setup() {
 		ProjectSettings::get_singleton()->set_custom_property_info("locale/fallback", PropertyInfo(Variant::STRING, "locale/fallback", PROPERTY_HINT_ENUM, options));
 	}
 #endif
-	//load translations
 }
 
 void TranslationServer::set_tool_translation(const Ref<Translation> &p_translation) {
@@ -1197,15 +1195,26 @@ void TranslationServer::set_tool_translation(const Ref<Translation> &p_translati
 }
 
 StringName TranslationServer::tool_translate(const StringName &p_message) const {
-
 	if (tool_translation.is_valid()) {
 		StringName r = tool_translation->get_message(p_message);
-
 		if (r) {
 			return r;
 		}
 	}
+	return p_message;
+}
 
+void TranslationServer::set_doc_translation(const Ref<Translation> &p_translation) {
+	doc_translation = p_translation;
+}
+
+StringName TranslationServer::doc_translate(const StringName &p_message) const {
+	if (doc_translation.is_valid()) {
+		StringName r = doc_translation->get_message(p_message);
+		if (r) {
+			return r;
+		}
+	}
 	return p_message;
 }