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, 8 insertions, 8 deletions

diff --git a/core/ustring.h b/core/ustring.h
index e70b2bfe27..33320a0a49 100644
--- a/core/ustring.h
+++ b/core/ustring.h
@@ -415,25 +415,25 @@ _FORCE_INLINE_ bool is_str_less(const L *l_ptr, const R *r_ptr) {
 
 /* end of namespace */
 
-//tool translate
+// Tool translate (TTR and variants) for the editor UI,
+// and doc translate for the class reference (DTR).
 #ifdef TOOLS_ENABLED
-
-//gets parsed
+// Gets parsed.
 String TTR(const String &);
-//use for C strings
+String DTR(const String &);
+// Use for C strings.
 #define TTRC(m_value) (m_value)
-//use to avoid parsing (for use later with C strings)
+// Use to avoid parsing (for use later with C strings).
 #define TTRGET(m_value) TTR(m_value)
 
 #else
-
 #define TTR(m_value) (String())
+#define DTR(m_value) (String())
 #define TTRC(m_value) (m_value)
 #define TTRGET(m_value) (m_value)
-
 #endif
 
-//tool or regular translate
+// Runtime translate for the public node API.
 String RTR(const String &);
 
 bool is_symbol(CharType c);