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, 3 insertions, 0 deletions

diff --git a/core/translation.h b/core/translation.h
index b9e07fa2b1..29a068f450 100644
--- a/core/translation.h
+++ b/core/translation.h
@@ -73,6 +73,7 @@ class TranslationServer : public Object {
 
 	Set<Ref<Translation>> translations;
 	Ref<Translation> tool_translation;
+	Ref<Translation> doc_translation;
 
 	Map<String, String> locale_name_map;
 
@@ -109,6 +110,8 @@ public:
 
 	void set_tool_translation(const Ref<Translation> &p_translation);
 	StringName tool_translate(const StringName &p_message) const;
+	void set_doc_translation(const Ref<Translation> &p_translation);
+	StringName doc_translate(const StringName &p_message) const;
 
 	void setup();