lang: Add support for raw catalog references with _R

_R marks a raw catalog entry as Referenced (= used) for cases where the
catalog pointers are handled at a lower level.

Firmware/language.h

@@ -46,6 +46,7 @@
 
 #define _N(s) (__extension__({static const char __c[] PROGMEM_N1 = s; &__c[0];}))
 #define _n(s) _N(s) // declare and return untranslated string
+#define _R(s) (s)   // return reference to translatable string (for warning suppression)
 
 /** @brief lang_table_header_t structure - (size= 16byte) */
 typedef struct

lang/lang-extract.py

@@ -149,8 +149,8 @@ def extract_refs(path, catalog):
 
     # match message catalog references to add backrefs
     RE_CAT = r'''
-        (?<!(?:/[/*]|^\s*\#) [^\n]*)         # not on a comment or preprocessor
-        \b (?:_[TO]) \s* \( \s* (\w+) \s* \) # $1 catalog name
+        (?<!(?:/[/*]|^\s*\#) [^\n]*)          # not on a comment or preprocessor
+        \b (?:_[TOR]) \s* \( \s* (\w+) \s* \) # $1 catalog name
     '''
 
     for m in regex.finditer(RE_CAT, source, regex.M|regex.X):